Veterinary Anatomy First Semester

 

Book Writter;

 

1.The anatomy of domestic Animal = S.Sisson and Groosman and R.Getty

2.Primary Veterinary Anatomy = RK Ghosh

3.Anatomy of Ox = D.Rhagwan

Anatomy: The word Anatomy is derived from Greek word (Anna+Temnein/ Tomy; Ana means to separate or apart from, tomy means to cut up). It signifies the cutting apart or disassociation of parts of the body.

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Definition: Anatomy is the branch of biological science which deals with the form and structure of an organisms.

Veterinary Anatomy: is the branch of Anatomy which deals with the form and structure of the principal domesticated animals and birds. It also includes wild animals and birds, as well as acquatic animals and birds, even the human being is also a part of Veterinary Anatomy.

Branches of Anatomy :

1.  Gross anatomy (Macroscopic anatomy) : deals with the study of form and structure of an organisms with  nacked eye or with hand lens.

2.  Histology (Microscopic Anatomy) : deals with the study of form and structure of  an organisms  with the help of microscope. 

3.  Ultra-structural Anatomy(Ultramicroscopic) : deals with the study of form and structure of an organisms  with the help of an electron microscope.

4.  Embryology/Developmental Anatomy : deals with the study of form and structure of an organisms from the time of fertilization/conception until adulthood.

5.  Systematic anatomy : deals with the study of individual system of a body by grouping the   various organs of a particular system.

6.  Topographic Anatomy : the term topographic anatomy designates the methods by which the relative positions of the various parts of the body are accurately determined.

7.  Applied Anatomy : the concideration of anatomical facts in their relation to surgery, physical diagnosis, and other practical branches is termed applied anatomy.        

8.  Surgical anatomy : deals with the site and tissues encountered during the surgical operations.

9. Radiological Anatomy : is the study of structure based on radiological appearance of tissues or organs with the help of X-rays.

10.  Pathological Anatomy : is the study of structure of abnormal, diseased or  injured tissue.

11. Functional Anatomy (Physiology) : is the study of function of different structures of an organisms.

12. Comparative anatomy : is the description and comparision of the structure of animals and forms the basis for their classification

13. Special Anatomy : is the description of form and structure of a single species.

14.Gerontological Anatomy : is the study of effects of aging and of age-related diseases. It is concerned with the problems of aging. 

Chief methods of study of Anatomy

Three chief methods of study are employed- systematic, topographic, and applied, but the latest method of study is the Regional Anatomy.

Regional Anatomy: is the method of study of Anatomy based on different regions of the animal body(for example, head, neck, trunk, forelimb, hindlimb, and tail), emphasizing the relationship of various systemic structures(for example, muscles, blood vessels, lymph vessels, nerves etc.), with reference to diagnosis and treatment of a disease or injury.

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Division of  Systematic Anatomy:

 

Systems	Name of the fields	Chief structures
Skeletal System	Osteology	Bones and Cartilage
Articular System	Arthrology /Syndesmology	Joints
Muscular System	Myology	Muscles
Digestive System	Splanchnology	Stomach and Intestine
Respiratory System		Trachea and Lungs
Urinary System		Kidney, Bladder and Urethra
Male reproductive System		Testes, Epididymis, Penis
Female reproductive System		Ovaries, Uterus, Vagina
Endocrine System		Ductless glands- Pituitary, Thyroid
Nervous System	Neurology	Brain and Spinal cord
Cardiovascular System	Angiology	Heart and Blood Vessels
Lymphatic System		Lymphoid system- Lymphnode
Sensory System	Aesthesiology	Eye, Ear, Nose, Tongue and Skin

TOPOGRAPHIC TERMS

1.       Directional planes:

         (Plane is a surface, real or imaginary, along which any two points can be connected by a  

          straight line) 

a.   Median plane/mid-saggital plane – it is an imaginary plane passing through the body 

cranio-caudally, which divides the body into similar right and left halves. 

    b.   Sagittal/para-median Plane – planes parallel to the median plane are sagittal.

    c.   Transverse/Segmental plane – is at right angles to the median plane and divides the body  

          into  cranial and caudal segments.

    d.  Horizontal/Frontal plane – runs at right angles to the median and transverse planes and    

      thus divides the body or head into dorsal and ventral portions for example : if a cow 

      walks into a lake until the water comes above the chest, the surface of the water  

      represents a horizontal plane in relation to the cow.'

2.       Directional terms:

1. Cranial (cranium : skull) – structure or surface lies towards the head end of the body.
2. Caudal (cauda : tail) – structure or surface lies towards the tail end of the body.
3. Rostral (rostrum : nose) – structures towards nose with respect to parts of the head.
4. Dorsal (dorsum : back) – towards the backbone or vertebral column.
5. Ventral (venter : belly) – towards the belly/abdomen or away from the vertebral column.
6. Medial – towards or relatively nearer to the median plane.
7. Lateral – away from or relatively farther from the median plane (antonym of medial).
8. Palmar – the term uses below the carpus to the aspect of forelimb (plam of the hand).
9. Plantar  – the term uses below the tarsus to the aspect of hind limb (sole of the foot ).
10. Proximal (proximus : near) – express relative distances of parts from the long axis of the                                                  body. Relatively near the main mass or body.
11. Distal (Distantia : distance) – away from main mass or body. Structure that lie at              Distance with the body.

  

 FEATURES OF BONE

1.  Articular projection :

         a.  Head/Caput – Nearly round, convex articular end. 

         b.  Condyle – A rounded protuberance at the end of a bone forming an articulation.

         c.  Trochlea – A pully like grooved articular surface.

               d.  Facet – A small, smooth and relatively flat articular surface.

2.   Articular depression :

          a.  Glenoid cavity – The socket that receives the head of humerus.

          b.  Glenoid fossa – The fossa of temporal bone that receives the condyle of the    

                                         mandible.

          c.  Cotyloid cavity – The socket (acetabulum) that receives the head of femur.

                d.  Notch – Articular curve or indentation (depression or hollow).

        C.   Non- articular projection :

a.       process – A projection or outgrowth of bone.

b.       Spine – A process in the form of an elongated evevation.

c.       line – A process is small and linear.

d.       ridge – A process is linear and thick and elongated.

e.       Crest – A process is sharp, rough and elongated.

f.       Tubercle – A small rounded rough elevation or eminence on a bone.

g.      Tuberosity – Prominent tubercle, an elevated round process of a bone.  

h.      Trochanter – Excessively developed tubercle.

i.        Epicondyle – Non articular eminece, attached to condyle.

j.        Cornu – Any projection like a horn or horn like process.

        D.  Non – articular depressions :

           a.    Fossa – A shallow depression in the form of blind cavities.

           b.    Fovea – A pit or cup like depression, smaller than fossa.

           c.    Groove  – A long narrow depression.

           d.    Foramen – Perforation of vessels and nerves.

           e.    Canal – Tunnel through more than one bones. 

           f.    Sinuses – Air spaces within the bones of the skull with indirect communication            

                                  to the exterior.

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OSTEOLOGY: is the division of systematic anatomy which deals with description of the skeleton (bones and cartilage).

SKELETON: The term skeleton is applied to the frame work of hard structures which supports and protects the soft tissues of animals. In the descriptive Anatomy of higher animals, it is usually restricted to the bones and cartilages, although the ligaments which bind these together might well be included.

  

Classification
                                                                        Skeleton

                                                                 

A.    Appendicular                         B. Axial                                       C. Visceral

	Include the bones of limbs; forelimb or thoracic limb, hindlimb or pelvic limb		Includes the bones of head, vertebral column, ribs and sternum		Includes certain bones developed in the substance of some of the viscera or soft organs

 

 

Skeletal formula – Express the number of total bones in the skeleton.

 Skeleton formula of domestic animals and fowl:

 

Region	Cattle	Horse	Dog	Pig	Fowl
Vertebral column	50	54	52	52	41
Ribs and sternum	27	37	27	31	15
Forelimb	50	40	80	80	28
Hindlimb	50	40	76	80	42
Skull	34	34	34	30	40
Viscreal bones	2	--	1	1	1
Total	211	205	270	274	167

Bone: is one of the hardest connective tissue of the body which is suited for its supportive and protective function in the skeleton.

 Classification: The bones (ossa) are commonly divided into four classes according to their shape and function.This classification is not entirely satisfactory; some bones, e.g., the ribs, are not clearly provided for, and other might be variously placed.

1. LONG BONES (ossa longa):  Long bones are typically of elongated cylindrical form with enlarged extrimities. They occur in the limbs, where they act as supporting columns and as levers. The cylindrical part, termed the shaft or body (corpus), is tubular and encloses the medullary cavity (cavum medullare), which contains the medulla or marrow.

2. FLAT BONES (ossa plana):  Flat bones are expanded in two directions. They furnish sufficient area for the attachment of muscles and afford protection to the organs which they cover. e.g., scapula and many bones of the skull. Flat bones consists of two layers of compact bone with intervening spongy bone and marrow. The spongy layer in the bones of the skull is termed diploe.

3.  SHORT BONES (ossa brevia): Short bones present somewhat similar dimensions in length, breadth and thickness. Their chief function appears to be that of diffusing concussion. e.g., carpus, tarsus and sesamoid bones. They diminish friction or change the direction of tendons  or increase leverage to muscles and tendons.

4. IRREGULAR BONES: This group include the bones of irregular shape and they are median and unpaired. Their functions are various and not so clearly specialized as those of the preceding classes. e.g., vertebrae and the bones of the cranial base.

     Functions:

              

·         Supports and protects the soft tissues of the body.

·         Plays vital role in the motility of the animal.

·         Important source of essential minerals like calcium and phosphorus.

·         Important source of blood cells like RBC, WBC, & platelets.

·         Provide body shape and bears the weight of animal body.

                                  

  STRUCTURE OF BONE

The architecture of bone can be studied best by means of longitudinal and transverse sections of specimens which have been macerated so as to remove most of the organic matter. These show that the bone consists of an external shell of dense compact substance, within which is the more loosely arranged spongy substance. In typical long bones the shaft is hollowed to form the medullary cavity.

Major constituents of bone

1. Periosteum
2. Compact bone
3. Spongy bone
4. Endosteum
5. The marrow

1) PERIOSTEUM – is the membrane which invest the outer surface of bone, except where it is covered with cartilage. It is a layer of specialized connective tissue. A periosteum layer is lacking on those areas of the epiphyses of long bones that are covered with articular cartilage. The periosteum consists of an outer protective fibrous layer and an inner cellular osteogenic layer. During active growth the osteogenic layer is well developed, but later it becomes much reduced. The fibrous layer varies much in thickness, being, in general, thickest in exposed situations. The adhesion of the periosteum to the bone also differs greatly in various places; it is usually very thin and easily detached where it is thickly Covered with muscular tissue which has little or no attachment.

2) COMPACT BONE – differs greatly in thickness in various situations, in conformity with the stresses and strains to which the bone is subjected. In the long bones it is thickest in or near the middle part of the shaft and thins out toward the extremities. It is specially dense and smooth on joint surface. Circumscribed thickenings are found at points which are subject to special pressure or traction.

3) SPONGY BONE – consists of delicate bony plates and spicules which runs in various directions and intercrosses. These are definitely arranged with regard to mechanical requirements, so that systems of pressure and tension plates can be recognized in conformity with the lines of pressure and the pull of tendons and ligaments respectively.The intervals between the plates are occupied lay marrow and are termed marrow spaces.The spongy substance forms the bulk of short bones and of the extremities of long bones; in the latter it is not confined to the ends but extends a variable distance along the shaft also.

Some bones contain air spaces within the compact substance instead of spongy bone and marrow and hence, are called pneumatic bones. The cavities are termed sinuses and are lined with mucous membrane; they communicate indirectly with the external air. In certain situations the two compact layers of flat bones are not separated by spongy bone, but fuse with each other; in some case of this kind the bone is so thin as to be translucent, or it may undergo absorption, producing on actual deficiency. The flat bones of the cranial vault and sides are composed of an outer layer of ordinary compact substance, the lamina externa, an inner layer of very dense bone, the lamina interna or tabula vitrea end between these a variable amount of spongy bone, here termed diploe.

4 ) ENDOSTEUM – the endosteum is a thin fibrous membrane which lines the medullary cavity

and the larger haversian canals (nutrient canal of bone).

5) THE MARROW – occupies the interstices of the spongy bone and the medully cavity of the  long bones. There are two varieties in the adult - red and yellow. In the young subject there is only red narrow but later this is replaced in the medullay cavity by yellow marrow. The red marrow contains several types of characteristics cells and is a blood forming substance, where as the yellow is practically ordinary adipose tissue. Yellow marrow is formed by regressive changes in red marrow, including fatty infiltration and degeneration of the characteristics cells; thus we find transitional forms or stages in the process. In aged or badly nourished subjects the narrow may under go gelatinous degeneration, resulting in the formation of gelatinous marrow. Red narrow persists in the sternum through out the life and thus, this is a convenient place for examination and aspiration.

DEVELOPMENT AND GROWTH OF BONE

The primitive embryonal skeleton consists of cartilage and fibrous tissue, in which the bones develop. The process is termed ossification or osteogenesis, and is effected essentially by bone-producing cells, called osteoblasts. It is customary, therefore, to designate as membrane bones those which are developed in fibrous tissue, and as cartilage bones those which are preformed in cartilage. The principal membrane bones are those of the roof and sides of the cranium and most of the bones of the face. The cartilage bones comprise, therefore, most of the skeleton. Correspondingly we distinguish intramembranous and endochondral ossification. In intramembranous ossification the process begins at a definite center of ossification (Punctum ossificationis),where the osteoblasts surround themselves with a deposit of bone. The process extends from this center to the periphery of the future bone, thus producing a network of bony trabeculae. The trabeculae rapidly thicken and coalesce, forming a bony plate which is separated from the adjacent bones by persistent fibrous tissues.

The superficial part of the original tissue becomes periosteum, and on the deep face of this successive layers of periosteal bone are formed by osteoblasts until the bone attains its definitive thickness. Increase in circumference takes place by ossification of the surrounding fibrous tissue, which continues to grow until the bone has reached its definitive size. In endochondral ossification the process is fundamentally the same, but not quite so simple. Osteoblasts emigrate from the deep face of the perichondrium or primitive periosteum into the cartilage and cause calcification of the matrix or ground substance of the latter. Vessels extend into the calcifying area, the cartilage cells shrink and disappear, forming primary marrow cavities which are occupied by processes of the osteogenic tissue. There is thus formed a sort of scaffolding of calcareous trabeculae on which the bone is constructed by the osteoblasts. At the same time perichondral bone is formed by the osteoblasts of the primitive periosteum. The calcified cartilage is broken down and absorbed through the agency of large cells called osteoclasts, and is replaced by bone deposited by the osteoblasts. The osteoclasts also cause absorption of the primitive bone, producing the marrow cavities; thus in the case of the long bones the primitive central spongy bone is largely absorbed to form the medullary cavity of the shaft, and persists chiefly in the extremities. Destruction of the central part and formation of subperiosteal bone continue until the shaft of the bone has completed its growth.

CHEMICAL AND PHYSICAL PROPERTIES OF BONE

Dried  bone consists of organic and inorganic matter in the ratio of approximately 1:2. The animal matter gives toughness and elasticity, the mineral matter gives hardness to the bone tissue. Removal of the organic matter by heat does not change the general form of a bone, but reduces the weight by about one third and makes the bone very fragile. Conversely, decalcification, while not affecting the form and size of the bone, makes it soft and pliable. The organic matter (ossein) when boiled yields gelatin. The organic portion of bone consists chiefly of a protein, called bone collagen or ossein. Bone itself is a highly specialized form of C.T. that is hard and white and contains cells peculiar to it.

The hardness of bone is due to the deposition of mineral salts within the soft organic matrix. In addition to containing water bone consists of two main components;

             1.  The organic framework, and

       2.  The inorganic mineral salts (bone ash)

Between the collagenous fibres a fluid is found, resembling tissue fluid, an amorphous ground substance(mucopolysaccharides, hyaluronic acid, condroitin sulphate, keratin, and electrolytes). The following table represents the composition in 100 parts of ox bone of average quality:

Gelatin ----------------------------------------------------- 33.30

Calcium phosphate --------------------------------------- 57.35

Calcium carbonate ----------------------------------------  3.85

Magesium phosphate -------------------------------------  2.05  

Carbonate and chloride of sodium ----------------------  3.45

                                                                                   100.00

Fresh dead bone has a yellowish white color; when macerated or boiled and bleached, it is white. The specific gravity of fresh campact bone is about 1.9. It is very hard and resistent to pressure. Its compressive strength is about 20,000 pounds per square inch, and its tensile strength averages 15,000 pounds per square inch.

 COMPOSITION OF BONE   

The hard extremely dense connective tissue that forms the skeleton of the body. It is composed of a matrix of collagen fibers impregnated with bone salts (chiefly calcium carbonate and calcium phosphate).

• Collagen fibers

by weight: 1/3 of bone

by volume: 1/2 of bone

• Hydroxyapatite crystals

                 (ca)10(PO4)6(OH)2

                 95% solid (Vs. Water)

                 65% mineral; 35% Organic

Organic matter:

The growth and development of the bone is possible due to the organic matter contained in it. Organic matters are present in the bone in the form of membrane, cartilage, marrow, vessels, nerves and included fluids.

Inorganic matter:

Inorganic matters are present in the from of salts, deposited during the process of ossification of bone. The strength and hardness of a bone is due to the inorganic salt constituents.  

 

Bones of Appendicular skeleton 

 General plan 

Appendicular skeleton: is the fundamental part of the skeleton which deals with the form and structure of the bones of the limbs, i.e. forelimb and hindlimb.

Fore limb/Thoracic limb (Four Segments)	Hind limb/Pelvic limb (Four Segments)
Thoracic Girdle/Shoulder/Pectoral Girdle       Scapula, Coracoid, and Clavicle   Arm (upper arm)       Humerus  Forearm       Radius/Ulna  Manus/ Forepaw       Carpus (wrist) – Carpal bones       Metacarpus – Metacarpal bones         Digit/digits – Phalanges and Sesamoid bones	Pelvic girdle/ Hip bone/Ossa Coxarum       Ilium, Ischium, and Pubis Thigh:       Femur Leg/Crus       Tibia/Fibula Pes/ Hindpaw       Tarsus(hock/ankle) – Tarsal bones       Metatarsus – Metatarsal bones       Digit/digits – Phalanges and Sesamoid                             bones

THE FORELIMB (OX)

• Forelimb is attached to the thorax by means of muscles of the thoracic girdle.
• It is divided into four segments in each leg.

        The shoulder girdle – consists of;

                                 Scapula (2)

                                 Coracoid (2)

                                 Clavicle (2)- may be absent or if present, it is embedded in the brachiocephalicus   muscle in the form of fibrous intersection.

         The arm – consists of;

                                  Humerus (2)

        The forearm – consists of;

                                  Radius/ulna (2)

        The manus – consists of;

• Carpus – consists of;

             Carpal bones (12)

• Metacarpus – consists of;

              Metacarpal bones (6)

• Digits (8) – consists of;

   Phalanges (12)

   Sesamoid (12)

              THORACIC/ SHOULDER GIRDLE/ PECTORL GIRDLE

Shape: Scapula is a flat, more regularly triangular bone than horse.

Location: It is located on the cranial part against the lateral wall of the thorax, being gently curved. Its long axis extends obliquely from the fourth thoracic spine to the sternal/ventral end of the first rib.

Direction: It is directed downward and forward. 

Relation/Articulation: It articulates with the humerus below forming a shoulder joint and medially attached with the thorax by means of muscles.

Composition:

It consists of 2 surfaces, 3 borders and 3 angles.

Surfaces: The scapula is wider above than below. The two surfaces are:

• Lateral Surface
• Medial Surface

           Lateral Surface:      

•          It is divided into two unequal areas (1:3) by the spine of the scapula.
•    The area in front or superior of the spine forms only one-fourth part and is termed as supraspinatus fossa and the area behind or inferior to the spine forms three-fourth of the dorsum and is termed as infraspinatus fossa.
•        The supraspinatus fossa lodges supraspinatus muscles where as infraspinatus fossa lodges the infraspinatus muscles. The infraspinatus fossa also bears roughened lines to which the teres minor muscle is attached.
•      The spine of scapula is wavy in outline. It marks a backward bend to about its middle and forward bend below. The free margin of spine is thickened in the middle for the attachment of the tarpezius muscle. The spine becomes more prominent below and is prolonged by a pointed projection, the acromion process which gives origin to the acromial part of the deltoid muscle.

         Medial Surface/Costal Surface:

•       Consist of a shallow subscapular fossa in the middle, which lodges(origin) the subscapularis   muscle.
•    At the upper part of this surface, cranially, there is a rough triangular area for the attachment(insertion) of serratus cervicis muscle.
•       A rough muscular line (at the caudal angle of scapula) posteriorly serves for the insertion of serratus thoracic muscle.

Borders:

   Three borders: Anterior, Posterior & Vertebral.

            Anterior border: Thin, sharp and convex in the dorsal two third and thick, rounded and concave for the remainder of its extent.

            Posterior border: Thick and slightly concavo-convex. Nutrient foramen is on lower-third of this border.

            Vertebral border: Thick and pitted for the reception of scapular cartilage, which posteriorly forms a rounded projection.

Angles:

    Three angles: Anterior/Cervical angle, Posterior/Dorsal angle & Inferior/Articular angle.

            Anterior angle: Thin and formed by the vertebral and the anterior border.

            Posterior angle: Thick and tuberous and is formed by the vertebral and posterior   

                                        borders.

           Inferior angle:

·         It is attached to the rest of the bone by a constriction, the neck of the scapula.

·         It is composed of a glenoid cavity and a tuber scapula.

·        The glenoid cavity is shallow, nearly circular, articular depression and meets the head  of the humerus to form the shoulder joint.

·         The rim of the cavity presents and undeveloped glenoid notch on its lateral aspect.

The tuber scapula is a rough eminence placed in front of the glenoid cavity and gives origin to the tendon of  the biceps brachii muscle. A short, rounded coracoid process projects from the medial side of the tuber scapula and gives origin to the coraco-brachialis muscle.

Spices difference of scapula:  

a) Scapula of  horse

• The spine is placed a little further backwards form  the  anterior border.
• Subscapular fossa is deeper.
• The tuber scapulae and  glenoid   cavity are placed further apart.
• Glenoid notch is deep and distinct.
• Acromion process is absent 

b) scapula of Dog

• Spine is placed in the middle and divides the lateral surface in two equal fossae
• Acromion process is short, blunt and overhangs the glenoid cavity.
• The subscapular fossa is very shallow.
• The anterior border is thin and convex. The posterior border is thick and nearly straight. The ventral  border is convex.
• Tuber scapulae is blunt.
• Glenoid cavity is prolonged forwards under the tuber scapulae.
• Small coracoid process is present. 
• (Note:- the shoulder girdle has three bones- the scapula, coracoid and the clavicle. The clavicle is embedded in the brachio-cephalicus muscle in front of the scapulo-humeral articulation. Clavicle is thin, small and irregular triangular, bony or cartilaginous plate. It doesn't articulate with the skeleton.)

 

 c) Scapula of Pig

• The ratio between supraspionus fossa and infraspinous fossa is 1:0.8
• Spine is wide and further directed backward.
• Acromion process is rudimentary.
• Glenoid notch is absent. 

d) Scapula of goat

•   Relatively smaller but more triangular and angular than ox.
• Subscapular fossa is more extensive, that is triangular in shape.

e) Scapula of Rabbit

•   Spine is situated more cranially.
•   Anterior angle is blunt.
•   Coracoid process is developed.
•   Metacromion process is present.

f) Scapula of fowl:

• It is elongated, narrow, thin slightly curved bone and situated backward parallel to the vertebral column reaching almost the pelvis.
• The anterior extremity is articular and   meets the coracoid and the humerus while the posterior end is free and non-articular.  

Pectoral Girdle of fowl

The pectoral girdle are composed of three pairs of bones which support the wings. They are formed by the fused clavicles (called furcula), the coracoids and the scapulae.

The most robust bone of the pectoral girdle is the coracoid, which is directed ventrally and caudally to articulate with the sternum at the coracoidal sulcus. The coracoids are hollow, being invaded by the clavicular air sacs.

 

The clavicles are slender rod-like bones which are ventrally fused into a flattened plate, the hypocleidium (furcular facet), which is connected to the carinal apex of the sternum by a ligament, the hypocleidial ligament, which also represents the raphe of the mojor flight muscle, the pectoralis.

The long, flat scapula extends caudally, paralleling the vertebral column; it is slightly thicker at its proximal end, and near the acromion process there is a pneumatic foramen. The scapula articulates cranially with the coracoid and furculum and participates with the former in the formation of the glenoid fossa, the articular fossa for the head of the humerus.

The three bones scapula, coracoid and furculum- come together dorsally leaving a triosseal canal (foramen triosseum) through which the tendon of the supracoracoideus muscle passes to insert on the humerus as an important part of the flight mechanism; it acts to elevate the humerus and the wing.

The HUMERUS

Shape: It is long cylindrical bone.

Location: proximal end of the forelimb.

Direction : Obliquely downwards and backwards.

Relation: It articulated with the scapula above and radius -ulna below. It forms shoulder joint above with the scapula and elbow joint below radius & ulna.

Composition: Consists of a shaft and two extremities .

1. Shaft : It is twisted, cylindrical and presents four surfaces .

    A. Anterior Surface: it is triangular , wide and smooth above and narrow below. It bears             muscular imprints in its middle and distal parts.

    B. Posterior Surface: It is rounded and smooth , and blends with the lateral surface .Nutrient Foramen is present at middle of the distal –third of this surface.

    C. Medial Surface : It is rounded, nearly straight and blends with the anterior and posterior surfaces. At the middle, the teres tubercle is present for the insertion of the teres major  m/s  n

    D. Lateral Surface: It has musculo-spiral groove which lodges the brachialis m/s . lateral surface is separated from the anterior surface by a distinct border, the deltoid ridge, which ends distally above the coronoid fossa. At the middle of the ridge, there is a prominence for the insertion of deltoid m/s, termed as Deltoid tuberosity . Extending from this deltoid tuberosity to the articular head, is a curved line to which the triceps m/s is attached.  Immediately behind  this curved line, placed on the extreme dorsal surface, is a nodule for the insertion of teres minor m/s.

 2. Extremities: Two

A. Proximal Extremity: It is voluminous part of bone and is composed of on articular head, two tuberosities and a bicipital groove.

i) Head: It is placed behind and is large, rounded, convex and double the size of the glenoid cavity of the scapula. Neck is the constricted part just below the head. 

ii) Tuberosity: Two: Lateral and Medial tuberosity separated by inter-tuberal groove.

a.       Lateral tuberosity : Large, prominent and rises above the head. It is situated on the antero- external part of the head and is divided into summit and a convexity. The summit forms the outer boundary of the bicipital groove and overhangs it. Below and external to the summit is a large, circular rough area, for the insertion of the infraspinatus m/s. The summit is attached to the lateral tendon of the supraspinatus m/s.

b.       Medial tuberosity : It is much small and is divided into two parts: anterior and posterior.

• Anterior Medial Tuberosity: It forms the medial boundary of the bicipital groove and curves over it. Its gives attachment to the medial tendon of the supraspinatus above and to the deep pectoral m/s below.
• Posterior Medial Tuberosity : it gives attachment to the sub-scapularis m/s.
•  Bicipital groove (inter-tuberal groove) : it is situated on the anterior part of the proximal extremity and is bounded by the anterior parts of the two tuberosities. The bicipital groove gives passage to the tendon of the biceps brachii m/s.

B. Distal Extremity: It is articular and is divided into two condyles: Medial (Trochlea) and Lateral (Capitulum) condyle, by an antero-posterior ridge. 

•   This end also consist medial and lateral epicondyle, olecranon fossa and the radial/ coronoid fossa.
•    The medial condyle is much larger than lateral and is transversed by an antero-posterior deep groove, which reaches the olecranon fossa. This extension articulates with the semilunar notch of the ulna posteriorly.
•    The lateral condyle is much smaller and is placed lower, which gives this extremity an oblique appearance. Anteriorly, above the articular area is a depression, the coronoid fossa, which receives the coronoid process of the radius during extreme flexion of the joint. Posteriorly, above the articular area, is much deeper oleranon fossa, which receives the olecranon process of the ulna during extreme extension of the joint if bounded on either side by a prominent ridge, the epicondyle.

•          The medial epicondyle gives origin to the flexor carpi radialis, pronator teres, flexor carpi ulnaris, superficial digital flexor and the humeral head of the deep digital flexor.
•           The lateral epicondyle gives origin to the ulnaris lateralis at its tuberous portion. Lateral epicondyle marks on its lateral aspect, the condyloid crest which forms posterior boundary of the musculo-spiral groove and gives origin to the extensor carpi radialis, common digital extensor and medial digital extensor m/s.

Comparative anatomy of humerus: 

A) Horse:

• Musculo-spiral groove is deeper and is more spirally curved.
• Nutrient foramen is placed on the distal-third of the medial surface.
• Deltoid tuberosity is better developed.
• Head is smaller, neck id less distinct.
• The bicipital groove is again divided by an intermediate ridge.
• Summit of the lateral tuberosity is not high and arched inwards.
• The ridge on the distal articular surface is less prominent. 

 

b) Pig :

• Both proximal and distal ends are inclined.
• Musculo-spiral groove is shallow.
• Supratrochlear foramen may be present.

c) Dog:

• Humerus is relatively long and slender, but is less spirally twisted.
• The deltoid tubersoity is ridge like.
• The teres tubercle is a raised rough area.
• The nutrient foramen is placed on the posterior surface.
• Head is rounded and strongly convex, the lateral tuberosity is single while the bicipital groove is undivided.
• The coronoid and olecranon fossa usually communicate by a large foramen (supratrochlear foramen).

d) Rabbit:

• Head is elongated.
• Deltoid tuberosity is in the form of a ridge.
• Musculo-spiral groove is shallow.
• Supra-trochlear foramen is present.

e) Fowl:

• Proximally, this bone articulates with scapula and coracoid.
• The pneumatic foramen is situated medially below the head.
• The body is less twisted.
• The head is oval in form.

 

Bones of forearm

The RADIUS & ULNA

• The bones of forearm region are radius and ulna, which are attached to each other by an interosseous ligament.
•  Forearm of ox is short, but is longer in small ruminants.
• The radius is bigger than ulna and is fully developed.
• The ulna, though placed higher than the radius, is partially developed.
• Before adultism is reached, the two bones fuse with each other and constitute a single bone, the Os antibrachii.

 The Radius (OX)

Shape: It is a long bone. Radius is larger (not longer) of the two bones of the forearm. It is slightly curved.

Location: Located at forearm and attached with ulna.

Direction: Placed in vertical direction.

    

 Relation: It articulates with the condyles of humerus above, forming an elbow joint and the carpus below, Forming a carpal joint (knee joint). Ulna is articulated on the lateral aspect of the posterior surface of the radius.

Composition: It has ONE shaft and TWO extremities.

1) Shaft:

•   Slightly curved longitudinally and flattened cranio-caudally.
•   Presents FOUR surfaces:

a)     Anterior Surface:

- It is convex, smooth and is covered by extensor  m/s of carpus and digit.

- Three wide vertical grooves present at its distal-third, namely: lateral, central and medial groove, for the accommodation of the tendons of the extensor m/s.

b)     Posterior Surface:

•   It is concave from above to downwards and flat from the side to side.
•   At the lateral part of this surface, there is an elongated rough area for the attachment of cranial surface of the shaft of ulna by interosseous ligament.
•   This rough area is interrupted at two places to form the proximal and distal radio-ulnar arches or proximal and distal interosseous spaces. The fusion between the two bones above the proximal interosseous space is not complete. These two spaces are connected together by an interosseous groove laterally, for the transmission of the interosseous vessels of the forearm.
•   The nutrient foramen is placed on the lateral aspect of the proximal radio-ulnar arch.

c)      Medial surface:

•   It is gently concave above, smooth and rounded in its distal two-third.
•   This surface blends with the anterior and posterior surfaces, and is mostly sub-cutanceous.
•   At the proximal end of this surface, there is a smooth area for the passage of the tendons of brachialis, which is inserted along with medial ligament of the elbow joint.

d)     Lateral surface:

•  It is slightly concave, rounded and smooth in its upper third, where it blends with the anterior and posterior surface.

2) Extremities:

 TWO extremities:

A)   Proximal Exremities:

•   It is articular and is divided by a deep antero-posterior grove into medial (larger) and lateral (smaller) parts.

•   It articulates with the distal extremity (condyles) of humerus.
•   The articular surface is surrounded by a bony rim, which presents in front, about its middle, a prominent lip like projection the coronoid process.
•   Posterioly, there are two large concave facets for articulation with the ulna.
•   At the antero-medial aspects, there is a large radial tuberosity for the insertion of the tendon of the biceps brachii m/s.
•   On either side, there are roughened medial and lateral tubercles to which the medial and lateral ligaments of the elbow joint are attached.

B)    Distal Extremity:

•   It is large and thick.
•   The articular surface is oblique and is composed of three surfaces/facets, which articulate, with the bones of the proximal row of the carpus.

•   Medial Facets is intermediate in size and articulates with the radial carpal.
•   Middle Facet is largest in size, wide and concave in front, gradually becomes narrower and pointed behind. It articulates with the intermediate carpal.
•   Lateral Facet is smallest in size and articulates with the ulnar carpal and is saddle shaped; its lateral part is completed by ulna. There is a rough transverse ridge on the posterior part above the non-articular depression.

The ULNA

Shape: Ulna is longer of the two bones of the forearm. It is ill developed.

Location: Located at forearm and attached/fused with radius except at the two interosseous spaces (proximal and distal interosseous spaces).

Direction: Placed in vertical direction

Relation: It is fused with the radius along its postero-lateral aspect.

Composition: It has ONE shaft and TWO extremities.

1) Shaft:

•   Slightly bent and roughly prism shape.
•   Presents THREE surfaces and THREE borders:

A)   Anterior Surface:

• It is apposed to the posterior surface of the radius.
• It is rough and fused with the postero-lateral aspect of radius except at the position of the two interosseous spaces (proximal and distal interosseous spaces).

• The surface at the level of proximal interosseous space is In the form of an arch. At the upper part of this surface, there are two articular facets for the articulation with the corresponding facets of radius.

B)    Medial Surface:

•  Narrow, concave, blends with the posterior surface and provides accommodation for flexor m/s.

C)   Lateral Surface:

• Narrow, nearly flat and faint ridge.

Out of THREE borders, the Medial and Lateral borders are fused with the radius and the posterior one is smooth and concave on its length.

2) Extremities:

• TWO extremities:

A)   Proximal Extremity:

•         It is elongated and comprise of the Olecranon process and the Semi-lunar notch (sigmoid cavity).
•          Olecranon Process is massive part of the bone and projects inwards and slightly backwards behind the distal extremity of the humerus. It has TWO surfaces and TWO borders:

       Surfaces:

•  Medial Surface is slightly concave and smooth.
•   Lateral Surface is slightly convex.

Borders:    

Anterior Border is short, thin and pointed at its distal part of this process to form a beak-like projection, the processes anconeus, which overhangs the semi-lunar notch. The free proximal end of the process which is rough and tuberous, forms the summit and gives insertion to the triceps brachii, the tensor fasciae anti-brachii and anconeus m/s. 

The Posterior Border is long, concave and reaches to the distal extremity.

Semi-lunar Notch: The semi-lunar notch is a semi circular out cut placed below the                processes anconeus.

•   Articulates with the posterior part of the distal extremity of the humerus.
•   Between the notch and the dorsal part of the anterior face of the shaft, there are two facets, which form synovial joints with those on the posterior aspect of the proximal extremity of the radius.

B)    Distal Extremity:

•  It is fused with the radius and projects below the level of radius to form the styloid process of the ulna and furnishes a part of the articular facet for the ulnar carpal.

Comparative Anatomy of Radius & Ulna:

A) Horse:

• Radius is the larger and longer of the two bones of the forearm.
• Radial tuberosity is larger and well marked.
• Distal articular surfaces are not oblique.
• Ulna does not take part in the formation of the lateral articular facet.
• The grooves on the antero-distal part of the shaft are better marked.
•  On the lower-third and towards the medial border of the posterior surface, there is a roughened elevation to which the superior check ligament/radial check ligament is attached.
•  Ulna is less developed and extends only to the distal-third of the radius.
• The distal interosseous space is absent.
• The semi-lunar notch is more extensive and triangular in outline. The facets placed below the notch are convex.
• The medial surface of the olecranon process is more concave.

B) Pig:

•  Radius is comparatively shorter and thin.
•  Ulna is massive and curved backward.
•   The interosseous space is very narrow.

C) Dog:

 

• Two bones of the forearm are separated and are in contact with each other by their extremities and permit certain degree of movement. The shafts of two bones are separated by narrow interosseous space and extend throughout the length of bones.
•  The anterior surface of radius is marked by a groove on its distal half for the passage of tendon of the extensor carpi obliquus.
•  On the posterior surface of the radius, the nutrient foramen is placed at the junction of the dorsal and middle-third of shaft.
•  The proximal extremity of radius is small and has distinct neck; present only one articular surface that is concave and articulates with lateral condyle of the humerus. The medial condyle of the humerus articulates with a facet on the semi-lunar notch of ulna.
•  On the posterior aspect of the proximal extremity, there is convex marginal articular area called circumferential articularis, for the attachment of ulna.
•  Radial tuberosity is small.
• Distal extremity of radius is much wider and presents an extensive articular surface for the carpus.
•  The medial border projects downwards to form the styloid process of the radius.
•  Ulna is an independent and well-developed bone, which crosses the posterior surface of the radius medio-laterally. The shaft of ulna is THREE sided at proximal end while rounded at distal end.
• The anterior surface of ulnar shaft is rough and nutrient foramen is nearer to the proximal end of the shaft.
• The proximal extremity is short, concave, smooth medially; convex and rough laterally. Below the semi-lunar notch is a narrow, transversely placed, concave, articular area that articulates with the circumferential  articularis of the radius.
• The distal extremity is prolonged into a blunt pointed styloid process of the ulna and articulates by a concave facet with ulnar carpal below and by a convex facet with the radius, antero-medially.

 D) Fowl:

• Ulna is comparatively massive than radius.
•  Both bones are in contact at two extremities.
• Interosseous space is wide.
• Semi-lunar notch is ill marked.

• GROSS STUDY OF CARPUS/CARPAL BONE

  Bones of the Manus
  

  

  Manus is the fourth segment of forelimb/thoracic limb

  It consists of three segments;

  • Carpus- consists of carpal bones
  • Metacarpus- consists of metacarpal bones
  • Digit/digits- consists of phalanges and sesamoid bones

  General plan for Carpus (in domestic animals and birds) 

  • A group of carpal bones are known as carpus.
  • Carpus is the first segment of manus.
  • Carpus consists of number of bones ranging from two to eight carpal bones in domestic animals and  birds.
  • These bones are arranged in two rows; i.e., proximal row and distal row.
  • The proximal row consists of two to four carpal bones and are arranged from medial to lateral as radial, intermediate, ulnar, and accessory carpal.
  • The distal row consists of zero to four carpal bones and are arranged in the same manner as first, second, third, and fourth carpal.
  • In case of fowl, the carpus consists of two bones, the radial and ulnar in the proximal row as   mammals. During fetal life the distal row of carpus is present which exist as cartilaginous bodies that fuse with the metacarpus as carpo-metacarpus.

  Carpus(ox)
  

  • It is the first section of the manus and consists of six short bones, arranged in two  rows; proximal and distal.
  • The bones of carpus are arranged between the radius-ulna above and metacarpal bones below.
  • The bones of the proximal row ( from medial to lateral) are: radial carpal ( scaphoid), intermediate carpal (semilunar), ulnar carpal (cuneiform), and accessory carpal (pisiform)
  • Bones of the distal row are: second & third fused carpal (os magnum) and fourth carpal (unciform).
  • The first carpal bone at the distal row is absent in cattle BUT present in pig, dog, rabbit and occasionally present in horse.
  

  Carpals of Proximal Row(ox)

  RADIAL CARPAL:

  Shape: It is small, and somewhat compressed transversely.
  Location: It is medial bone of the proximal row.
  Relation/Articulation: 
             Proximally- the radius.
             Distally- the second & third fused carpal. 
  
             Laterally- the intermediate carpal and. 
  
             Medially- free.
  Composition: It presents SIX surfaces of which THREE are articular
  A)   Proximal Surface: is wide and convex in front; narrow and concave behind this surface articulates with the medial facet on the distal extremity of the radius.
  B)    Distal Surface: is similar but narrower in front and wider behind. It articulated with the medial facet on the proximal surface of the second and third fused carpal bone.
  C)   Lateral Surface: has upper and lower elongated facets for articulation with the medial surface of the intermediate carpal. The area between these two facets in rough and excavated.
  D, E & F) Anterior, Medial and Posterior Surface: are continuous, rough and non-articular. The anterior surface is convex, the medial surface is slightly depressed and the posterior surface bears tubercles on its lower aspect.
  
  

  INTERMEDIATE CARPAL:

        Shape: It is somewhat wedge shaped, being constricted in the middle and wider palmarly.
  Location: It is second and the central bone of the proximal row of the carpus.
  Relation/Articulation: 
               Proximally- the radius. 
  
               Distally- the second + third fused carpal and fourth carpal. 
  
               Laterally- the ulnar carpal. 
  
               Medially- the radial carpal.
  Composition: It presents SIX surfaces of which FOUR are articular
  A) Proximal Surface: is convex in front; concave behind, tapering medially and articulated with the middle facet on the distal extremity of the radius.
  B) Distal Surface: is convexo-concave and is crossed by a ridge, which divides the surface into two unequal halves. The medial facet articulates with the lateral facet on the proximal surface of the 2nd & 3rd fused carpal bone. The lateral facet is larger and articulates with the medial facet on the proximal surface of the 4th carpal.
  C) Medial Surface: has tow facets separated by a rough excavated area for the articulation with the redial carpal.
  D) Lateral Surface: is larger and has facets similar to those on the medial surface; these articulate with the facets on the medial surface of the ulnar carpal.
  E) Anterior Surface: is convex and rough for ligamentous attachment.
  F) Posterior Surface: is narrow and bears a tubercle on its lower part.
  
  

  ULNAR CARPAL:

  Shape: It is large and very irregular bone.
  Location: The ulnar carpal is the outermost bone, situated lateral to the intermediate carpal.
  Relation/Articulation: 
            Proximally- ulnar carpal articulates with the radius and the styloid process of ulna.
            Distally- the fourth carpal.
            Medially- the intermediate carpal.
            Posteriorly- the accessory carpal.
  
  
  Composition: It presents SIX surfaces of which FOUR are articular
  A) Proximal Surface: has concave facet that extends over the lateral surface. It articulates with the lateral facet on the distal extremity of the radius and styloid process of the ulna.
  B) Distal Surface: is small, concave and articulates with lateral facet on the proximal surface of the 4th carpal.
  C) Medial Surface: have two facets on its anterior part, which articulates with the intermediate carpal. The area between two facets is rough and excavated.
  D) Posterior Surface: is oblique and has an oval facets for articulation with the accessory carpal below this facet, the bone is extend in tuberous form.
  E & F) Anterior and Lateral surfaces are non-articular, continuous and rough.
  
  

  ACCESSORY CARPAL

  •     It is short, thick, rounded piece of bone.
  •     It is placed behind the ulnar carpal.
  •     Its anterior surface has an oval concave facet for articulation with ulnar carpal.
  •     The medial surface is concave while lateral is convex.
  •    This bone articulates with the ulnar carpal anteriorly.
  
  Carpals of  Distal Row
  
  
  The First Carpal bone is absent in cattle. The distal row consists second and third fused carpal(medially) and the fourth carpal(laterally).
   
  
  Second and Third Fused Carpal
  
  
  Shape: The second and third carpal bones are fused to form a large quadrilateral bone. It is larger than fourth carpal.
  Location: Situated medially at the distal row.
  Relation/Articulation:
              Proximally- Articulates with the radial and intermediate carpal.
              Distally- Articulates with large metacarpal
              Laterally- Articulates with fourth carpal bone.
              Medially- free.
  Composition: It has SIX surfaces of which THREE are articular
  • The proximal surface: is wide and bears a concavo- convex articular surface divided by a ridge into two unequal halves. The medial facet of this surface is larger and articulates with the distal surface of the radial carpal. The lateral facet, is similar but narrower, and articulates with the medial facet on the distal surface of the intermediate carpal bone.
  • The lateral surface: bears two facets for articulation with medial surface of the 4th carpal bone. The area between these facets is rough and excavated.
  • The distal surface: is flat and undulating (wavy outline), and articulates with the large metacarpal bone.
  • The anterior and medial surfaces: are non-articular, continuous and convex, and rough for ligamentous attachment.
  • The posterior surface: is narrow and non-articular.

  Fourth Carpal

  Shape: It is smaller quadrilateral  bone of distal row. It is thicker in front than behind.
  Location: It is located laterally at the distal row.
  Relation/Articulation:
   Proximally- Articulates with ulnar carpal and intermediate carpal.
              Distally- Large metacarpal.
              Medially- Second and third fused carpal bone.
              Laterally- Free.
  Composition: It has SIX surfaces of which THREE are articular
             
  Proximal surface: Articulates with intermediate carpal and ulnar carpal and is divided by an anterior-posterior ridge into two oblique areas. The medial facet is concavo-convex and articulates with the lateral facet on the distal surface of the intermediate carpal. The lateral facet is divided into two concave areas.
  Medial surface: Presents two facets for articulation with the 2nd and 3rd fused carpal bone. The area between these facets is rough and excavated.
  Lateral surface: It is encroached ( gradually intrude on others area), by the proximal surface and therefore, is very narrow, non- articular.
  Anterior surface: It is convex, rough and continuous with the lateral surface, non articular.
  Posterior surface: It is rough and tuberous and is non-articular.
  Distal surface: It articulates with smaller articular area on the lateral side of the proximal extremity of the large metacarpal bone.
  
  Comparison with:

  A. Carpal bones of Horse:

  
  

  
  

  • -        Consists of 7 bones, 4 in the proximal row and 3 in the distal row. Sometimes eight bones are present, when the first carpal is added.
  • -         Bones in the proximal row are larger, more regular and shape resembles with the bones of ox.
  • -         The radial carpal is the largest of the proximal row which is somewhat compressed and clearly six sided.
  • -         The intermediate carpal is somewhat wedge shaped which bears a concave facet proximally for articulation with the radius.
  • -         The ulnar carpal is smallest and most irregular bone of proximal row.
  • -         The accessory carpal is flat, discoid and has a regular circumference. The lateral surface is grooved for the passage of the tendon of the ulnaris lateralis m/s.
  • -         The first carpal bone is nodular when present and is placed behind the second carpal.
  • -         The second carpal bone is the medial bone of the distal row and is irregularly hemispherical. It articulates distally with the 2nd and 3rd metacarpal bones.
  • -         The third carpal  is the largest of the distal row, and is placed centrally. It is flattened proximodistally. It articulates distally with 3rd metacarpal bone.
  • -         The fourth carpal bone is larger than second carpal bone and bears a tubercle posteriorly. It is somewhat wedge shaped. It is the lateral bone of the distal row and articulates with 3rd and 4th metacarpal bones.
  

  B. Carpal bones of pig:

  • The carpus comprises eight bones, four in each row.
  • The bones of the proximal row resemble those of the ox, with exception of the accessory, which is more like that of the horse, but has no lateral groove.
  • The 1st carpal is small, elongated from before backward, rounded and articulates in front with second carpal.
  • The 2nd carpal is high and narrow, and articulates with 2nd & 3rd metacarpal bones distally.
  • The 3rd carpal articulates with the radial and intermediate above, the third metacarpal bone below.
  • The 4th carpal is the largest bone of the row; articulates with the intermediate and ulnar above, the 4th & 5th metacarpals below, and bears a tuberosity.
  

  
  

  C. Carpal bones of Dog:

  • Carpus consists of 7 bones, 3 in the proximal row and 4 in the distal row.
  • The radial and intermediate carpal bones are fused to form a single bone, and articulate distally with 1st, 2nd, and 3rd carpal bones of distal row.
  • The ulnar carpal bone is small and distally articulates with the 4th carpal and extends downwards to articulate with the 5th metacarpal.
  • The accessory carpal bone is cylindrical, being constricted in the middle and has two facets on its anterior extremity, one for the ulna and other for ulnar carpal.
  • The first carpal bone is smallest and articulates distally with the first metacarpal bone.
  •  The 2nd carpal bone is wedge shaped and articulates distally with the second metacarpal bone.
  • The 3rd carpal bone is similar to the 2nd, but larger, and articulates distally with the 3rd metacarpal.
  • The 4th carpal bone is the largest and articulates with 4th and 5th metacarpal bones.
  

  
  

  D. Carpal bones of Goat:

  • The carpal bones resemble those of the ox except in size.
  • The accessory is long and less tuberous.

  E) Carpal bones of fowl:

  • There are 2 bones: – Radial and Ulnar carpal at the proximal row. 
  • The bones the distal row are fused with the metacarpal bones.
  • 
    

    GROSS STUDY OF MANUS (DIGIT/DIGITS)

    
    
    

    
    

    DIGITS (OX)

    • Digit/digits are the third section of manus which is four in number in ox.

    • The digit or digits are the collective name of first phalanx, second phalanx, and third phalanx.

    • The large metacarpal bone, separates at the distal extremity into two condyles and each condyle carries one digit and each digit carries three phalanges and three sesamoid bones.

    • In ruminants (cattle, sheep, and goat), there are four digits in each leg of forelimb, namely; second, third, fourth, & fifth.
    • Among these, third and fourth digits are well developed and carries three phalanges and three sesamoids each.
    • The second and fifth are vestiges represented only by small dew claws at the back of fetlock joint; each contains one or two small bones which do not articulate with the rest of the skeleton.
    
    THE FIRST PHALANX (Os Suffraginis)
    Shape: It is long bone, more or less cylindrical.
    Location: Placed between large metacarpal above & second phalanx below.
    Direction: Placed obliquely downward & forward.
    Articulation: It articulates proximally with the distal extrimity of metacarpal and proximal sesamoid bones forming a fetlock joint and distally with the second phalanx forming a pastern joint.
    
    
    

    

    
     
    Composition: It presents a shaft & 2 extremities
    A) Shaft:
    • Thicker above than below.
    • The anterior surface is rounded from side to side and blends with the lateral         surfaces.  
    • The posterior surface is irregularly depressed and has nodular elevation at middle on either side for the ligamentous attachment.
    • The interdigital surface, which is nearly, flat and rough. The proximal inter-digital ligament is attached to this area.
    
    
    B) extremities: two 
    
    
    Proximal extremity
    • It is larger than distal extremity, and articulates with the distal extremity of large metacarpal bone.
    • It presents an articular surface, which is concave form before backward and is divided into two areas by an antero-posterior deep groove.
    • The lateral articular surface is larger and higher in level then medial surface.
    • Behind the articular area there are two facets for articulation with the proximal sesamoid bones.
    
    
    Distal extremity
    • It is smaller than the proximal extremity and articulates with the proximal extremity of the second phalanx.
    • The surface is divided by an antero-posterior groove into two condyles. The lateral is larger than medial.
                                
    THE SECOND PHALANX (Os Corona)
     
    Shape: it is a long bone, more or less cylindrical and contains a small medullary cavity.
    Location:  Placed between first phalanx  above & third phalanx below.
    Direction: Placed obliquely downward & forward.
    Articulation: It articulates proximally with the distal extrimity of first phalanx forming a pastern joint and distally with the third phalanx and distal sesamoid bone forming a coffin joint.  
                                   
    Composition : It presents a shaft & 2 extremities
     A) Shaft:
    •  Has three sides
    • The posterior surface is nearly flat or slightly concave.
    •  It is rendered short by the encroachment of the distal articular surface.
    • The lateral surface is convex, rounded and rough for ligamentous attachment.
    • The interdigital surface is depressed.
    
    

    B) extremities: two 

    
    
    Proximal extremity
    •  It presents an articular surface, which is divided by an antero-posterior faint ridge into  two concave areas, the lateral of which is larger and lower in position than the medial.
    • The articular surface, anteriorly, forms a prominent projection.
    •  Posteriorly, there are two tubercles and a depression, which are intended for the attachment of the tendons of the superficial digital flexor muscle.                              
    
    
    Distal extremity:
    • It is condyloid and is divided by an antero-posterior groove into two articular area, the lateral of which is larger than the medial.
    • The articular surface encroaches considerably on the anterior and posterior surfaces.

    THE THIRD PHALANX (Os pedis)

    •  It is the terminal bone of each digit and is enclosed entirely by hoof with which it bears close resemblance.
    • Proximally, it articulates with the distal end of the second phalanx.
    Composition:  the bone presents, 4 surfaces and 6 borders.
    
    
      A) Surfaces:
    1)Lateral surface :
    •  It is rough and traversed a little below its middle by a shallow groove running antero-posteriorly along which there are large numbers of foramina.
    • The area below the groove is prominently raised, rough and porous while the area above the groove is rough and perforated by a number of small foramina.
    • The posterior part is very steep.
    2. The medial/ Inter-digital surface:
    •  It is smooth and is marked by an antero-posterior groove along which there are  a large  number of foramina
    • The part above the groove is rough and porous.
    3)The ventral /Sole surface
            It is nearly flat being slightly concave in front.
    
    
    4) The dorsal /Articular surface:
    • It is concave and slopes downward and backward.
    • It is divided by an antro-posterior faint ridge into two areas, of which, the lateral being larger & higher in level than medial.
    • It presents posteriorly a trsnsverse concave facet for articulation with distal sesamoid.
    
    
    B) Borders: 
    1)     Anterior border: it is vertical, slightly convex and sharp.
    
    
    2)     Dorso-lateral  border: It is convex &separates the articular and lateral surfaces.
    
    
    3)     dorso-medial borer: It is convex& separates ventral and lateral surfaces
    
    
    4)     ventor-lateral border: It is convex & separtes ventral sufaces.
    
    
    5)     ventro-medial border: It is nearly straight and sharp & separates the  medial and ventral surfaces.
    
    
    6)     posterior border: It is thick and rounded.
    
    
    Comparison with:
    a.Phalenges of Horse
    
    

    

    
    b)     Phalanges of Dog
    • The first digit has only two phalanges due to which this digit fails to contact with ground while walking.
    • The rest of digits have three phalanges each.
    • 3rd &4th digits are largest.
    • The two phalanges of the first digit resemble with the 1st & 3rd  phalanges of other digits.
    • The1st& 2nd phalanges are the longer bones. The shaft of 1st phalanx of all digits (except the first) is four sided and is slightly bend.
    • The 2nd  phalanges are about two-third of first, in length.
    • The 3rd phalanx, which resemble to the claws, are hook like. 
    

    
    
    c)      Phalanges of Pig:
    • Each digit has three phalanges.
    • The phalanges of 3rd &4th digit are well developed.
    • The phalanges of 2nd & 5th digit are small and generally don’t reach to the ground.
    

    
    
    d)     Phalanges of fowl:
    
           There are three digits in numbers and are present at the terminal segment of the
         wing.
         The 2nd and 3rd digits consist of two phalanges and 4th digit has only one phalanx.
         3rd digit is the largest.
      
    

       Fig: Radius-ulna and manus showing phalanges of chicken

    11. Second digit (phalanges first and second)
    13. Third digit (phalanges first and second)
    14. Fourth digit (first phalanx)   
    
    

     The SESAMOIDS (OX)

    • Sesamoid bones are arranged in two rows, namely; proximal and distal rows.
    • Proximal sesamoids are situated behind the proximal end of first phalanx at the level of metacarpo-phalangeal articulation or fetlock joint.
    • Distal sesamoids are situated behind the distal phalangeal articulation in between the second and third phalanx at the level of pastern joint.
    • These are small bones and may be included in the group of short bones.
    
    
    Proximal Sesamoids:
    

    • The proximal row consists of two bones for each digit. 
    • The total number of sesamoid is four, two for each digit in one limb.
    • The bones of each pair articulate with the corresponding part of the distal end of the large metacarpal bone by their dorsal surface, with each other and with the 1st phalanx by small facets.
    • The apex is pointed dorsally and a slip of suspensory ligament is attached to it.
    
    
    Distal Sesamoid:
    

    • The distal row consists of one bone for each digit.
    • The total number of sesamoid is two, one for each digit in one limb.
    •  It is short bone and is placed transversely behind the distal phalangeal articulation.
    •  Their ends are narrower than proximal.
    
    
    Comparison with:
    
    
    A) Sesamoids of Horse:
    •   There are two proximal sesamoids in each limb and much larger than those of ox.
    •   These are pyramidal in shape.
    •   The two sesamoids articulate with the large metacarpal but don’t articulate with each   other or with 1st phalanx as in ox.
    •   The distal sesamoid is single and is shuttle shaped known as "navicular bone". It is  larger and longer than that of   the ox.
    
    
    B) Sesamoids of Dog:
    •  Proximal sesamoids are anterior and posterior.
    • Anterior sesamoids are five in number and each is in the form of a nodule in metacarpo-phalangeal joint of each digit.
    • Two posterior sesamoids are present behind each  metacarpo-phalangeal joint form  2nd to the 5th digit while 1st digit usually has single, flattened sesamoid; exceptionally, two are present.
    • The distal palmar sesamoids remain cartilaginous.
    
    
    C)  Sesamoids of Pig:
    •      There are two proximal and one distal sesamoid bones in each chief digit where as each accessory digit comprises two proximal sesamoid bones only.
    Notes:
    • Cow, sheep & goat have two principal digits or toes; the 3rd & 4th, while the 2nd & 5th    digits are represented only by small dew claws.
    •  In the pigs the dew claws are much better developed and are 2nd & 5th digits.
    • The dogs normally have 5 digits on each fore limb. The 1st digit is only dew claw and   corresponds in position of human thumb.
    • 
      

      Pelvic Girdle/Bony Pelvis

        
      

       The bones of hind limb consists of four segments

      1. Pelvic girdle/Bony pelvis:
            Hip bone/Ossa Coxarum and sacrum
            Hip bone consists of os coxae of both sides
            Os-coxae consists of three bones on each side 
            Ilium, Ischium, and Pubis
      2. Thigh:
            Femur
      3. Leg/Crus
            Tibia/Fibula
      4. Pes/ Hindpaw
            Tarsus(hock/ankle) – Tarsal bones
            Metatarsus – Metatarsal bones
            Digit/digits – Phalanges and Sesamoid bones
      

      1.  PELVIC GIRDLE (BONY PELVIS)

      

       

      

      
      

        The PELVIC GIRDLE (BONY PELVIS)
      

      • The PELVIC GIRDLE consists of two similar bones, the os-coxae of both sides and the sacrum.
      • Each os-coxae consists of three bones, namely; ilium, ischium, and pubis which are  fused ventrally at symphysis pelvis/pelvic symphysis forming ossa-coxarum.
      • Symphysis pelvis consists of ischial symphysis anteriorly and pubic symphysis      posteriorly.
      • Ossa-coxarum consists of two two ox-coxae of each side,which form a cartilaginous joint along the median line(pelvic symphysis).
      
      
      PELVIS 

      The bony pelvis is composed of ossa-coxarum, the sacrum and the first few coccygeal/caudal vertebrae.

      The bony pelvis(similar to basin) is bounded by pelvic bones and encloses a space called the pelvic cavity.

      The cavity is simple ovoid and is free in communication with the abdominal cavity in front.

      The floor and the roof of the pelvic cavity are not correspondingly placed. The floor or ventral wall is formed by the pubis and ischium bones and the roof or dorsal wall is formed by the sacrum and first few coccygeal vertebrae. The lateral walls are formed by the parts of ilium, sacro-sciatic ligament and acetabular part of ischia. .

      Anterior part of the roof has no bony floor, hence it is called false pelvis.

      The cranial opening of the pelvis is known as pelvic inlet or anterior aperture, which is formed dorsally by the sacrum base(sacral promontory), laterally by the shaft of the ilia(arcuate line/ilio-pectinal line) and ventrally by anterior border of the pubis(pecten ossis pubis).

      The pelvic inlet has two principal diameter. The conjugate or sacro-pubic diameter, measured from the sacral promontary to the pecten ossis pubis. The transverse diameter is measured at the greatest width, i.e., just dorsal to the psoas tubercle.  

      The pelvic outlet or posterior aperture is smaller and incomplete at the sides which is bounded dorsally by the third or fourth coccygeal vertebra, and ventrally by the ischial arch and laterally by the broad sacro-tuberal ligament and semi-membranosus muscle, thus enclosing perinium.
      
      
      
      

      OS COXAE/HIP BONE

      • The os-coxae or hipbone is the largest of the flat bones.
      • It consists of 3 bones primarily, the ilium, ischium, and pubis which meet together to form the acetabulum or cotyloid cavity, on each side which articulates with the head of femur.
      • These bones are fused in the adult usually by 7 to 10 months, but it is convenient to describe them separately.
      • It is a flat irregular bone, being directed obliquely downward and backward.
      
      

      THE ILIUM:

      • It is smaller than ischium and is irregularly triangular in shape.
      • It is present at the cranio-lateral aspect of the pelvis.
      • The bone is flat and expanded above, narrow in the middle and slightly expanded below.
      • The narrow part is the shaft of the ilium and is short and flattened from side to side.
      • The wide proximal part of the bone is called wing of the ilium.
        It presents 3 surfaces, 3 borders & 3 angles
      
       
      Surfaces:
      
      
      A) Gluteal Surface
      B) Iliac/Anterior Surface
      C) Pelvic/ Sacral surface
      
      
      A) Gluteal Surface:
      • Gluteal surface faces upward and outward.
      • It is concave at the proximal part and concavo-convex ventrally.
      • Parallel to the lateral border, there is a prominent oblique ridge called gluteal line, which becomes continuous ventrally with superior ischiatic spine.          
      • Nutrient foramen is placed on the gluteal line close to the posterior border.
      • Medial & deep gluteus muscle is attached to this surface. 
      B) Iliac/ Anterior Surface:
      • This surface faces forward, and is smooth and covered by iliacus muscle.
      • Just above the acetabulum, there is deep depression for the attachment of the rectus femoris muscle. 
      C) Pelvic/ Sacral Surface:
      • This surface faces inwards, towards the pelvic cavity.
      • Surface is wider at proximal and distal parts, but is narrow in the middle.
      • The proximal wider part posses a triangular articular  facet, which join with sacrum, forming sacro-iliac articulation. The margin of this facet is rough for attachment of sacro-iliac ligament.
      Borders:
      
      
      A) Lateral / Cotyloid Border
      B) Dorsal Border
      C) Medial Border
                  a) Anterior / Public Border
                  b) Posterior / Ischiatic Border 
      
      
      A) Lateral / Cotyloid Border:
      • It is concave, rough, separates the gluteal & the iliac surfaces and reaches the cotyloid cavity. 
      B) Dorsal Border:
      • It is thick, rough, concave and irregular, and forms the iliac crest on either end forming an angles.
      C) Medial Border:
      • It is concave and at the beginning of the shaft, it is divided into anterior(public) and a posterior(ischiatic) border.
       
      a) Anterior/Public border/Ilio-pectinal line:
      • It is rounded concave ridge.
      • It begins in front and below the articular facet and joins the anterior border of the pubis.
      • It separates iliac and pelvic surfaces and forms the lateral boundary of the pelvic brim.
      • About middle of this line, there is psoas tubercle on which psoas minor muscle is inserted. 
      b) Posterior/Ischiatic Border:
      •  It is deeply concave and forms about its middle, the anterior boundary of the greater schiatic foramen through which nerves and anterior gluteal vessel passes.
      • At its lower area, above the level of cotyloid cavity, this border is raised to form a part of superior ischiatic spine, which gives attachment to sacro-sciatic ligament.
      • It separates the gluteal and the pelvic surfaces and is continued on the ischium.
      
      
      Angles:
      
      
           A) External angle / Tuber coxae
           B) Internal angle / Tuber sacrale
           C) Ventral angle
      
      
      A) External angle / Tuber coxae
      • It is very large, prominent and is compounded of the three tuberosities. 
      B) Internal angle / Tuber sacrale
      • It is a little below the level of the sacral spines and lies opposite to the first sacral spine.    
      C) Ventral angle
      • It is the lower extremity of the bone.
      • It meets the ischium and pubis at cotyloid cavity.

       THE ISCHIUM:

      •  It is larger in size than ilium and is placed behind the ilium and the pubis.
      • It is directed obliquely upward and backward.
      • The transverse axis is pointing downward and inward; hence the pelvic floor is deeply concave.
           It presents 2 surfaces, 4 borders & 4 angles.
      
      
      Surfaces:
      
      
      A) Pelvic Surface
      B) Ventral Surface
      
      
      A) Pelvic Surface:
      • It is smooth and concave and forms the posterior part of the pelvic floor.
      • Just behind the anterior border, which forms the posterior margin of the obturator foramen, there is smooth, wide and less distinct groove for the attachment of the tendon of obturator internus muscle. 
      B) Ventral Surface:
      • It is nearly flat and presents a less developed, curved ridge about its middle, which extends either from the ventral surface of the tuber ischii or from the middle of this surface to terminate into a tubercle.
      • Biceps femoris muscle originates on the ridge and the tubercle.
      • The area lateral to the ridge, presents muscular imprints for the origin of gemelli muscles.
      
      
      Borders:
      
      
                  A) Anterior Border
                  B) Posterior Border
                  C) Medial Border
                  D) Lateral Border
      
      
      A) Anterior Border:
      • It is concave and forms the posterior margin of the obturator foramen.
      B) Posterior Border:
      • It is thick and rough. It slopes inward and forward to meet the border of opposite side forming the ischial arch.
      
      
      C) Medial Border:
      • It meets the opposite bone at symphysis ischii, which ventrally marks a roughened ridge terminating anteriorly into a tubercle.
      
      
      D) Lateral Border:
      • It is thick smooth and concave, and forms the lesser sciatic notch over which passes the posterior gluteal vessels.
      
      
      Angles:
                                       A)   Antero-Internal Angle
      
      B)    Antero-External Angle
      C)    Postero-Internal Angle
      D)   Dostero-External Angle
      
      
      A)   Antero-Internal Angle:
      
      • The symphyseal branch of the ischium meets the pubis at this angle, and with it forms the internal boundary of the obturator foramen.
      B)    Antero-External Angle :
      
      • The acetabular branch of the ischium meets the ilium and pubis at this angle in the cotyoid cavity.
      C)   Postero-External Angle :
      
      • This angle meets the same angle of the opposite bone at the ischial arch. 
      D)   Postero-External Angle:
      
      • It is rough and thick.
      • It forms trifid process (three sided mass) called tuber ischii, to which the sacro-sciatic ligament, biceps femoris, semitendinosus, semimembranosus and ischio-cavarnosus muscles are attached.
      
      

      THE PUBIS:

      • It is smallest bone of os-coxae and is placed between the ilium and the ischium.
      • It is irregularly triangular and forms the anterior part of the pelvic floor. 
      It presents 2 surfaces, 3 angles and 3 borders
      Surface:
      
      
      A)   Pelvic Surface
      B)    Ventral Surface
      
      
      A)    Pelvic Surface:
      • It is smooth and rounded & large urinary bladder is placed on it.
      
      
      B)    Ventral Surface:
      • It is smooth and slightly convex.
      
      
      Borders:
      
      
                  A) Anterior Border
                  B) Medial Border
                  C) Posterior Border
      
      
      A) Anterior Border:
      • It presents an oblique sub-pubic groove.
      • Lateral of this border, there is ilio-pectinal eminence, to which the common pre-public  tendon is attached that gives insertion to the abdominal muscles(e.g., obliq.ext. abdominis & rectus abdominis muscle).
      B) Medial Border:
      • It joins the same border of opposite bone at the symphysis pubis.
      
      
      C) Posterior Border:
      • It is concave and forms the anterior boundary of the obturator foramen, and is marked laterally by the obturator groove.
      
      
      
      Angles:
      
      
                      A)     Antero-Internal Angle
                       B)     Antero-External Angle
                       C)     Posterior Angle
      
      
      A) Antero-Internal Angle:
      • It is opposite to the same angle of opposite bone at the anterior end of the symphysis pubis.
      B) Antero-External Angle:
      • It joins the ilium and ischium at the acetabulum.
      C) Posterior Angle:
      • It meets antero-internal angle of the ischium, with which it forms the inner boundary of obturator foramen.

      The Acetabulum:

      • The acetabulum/cotyloid cavity is formed by the union of ilium, ischium and pubis.
      •   It articulates with the head of femur.
      • It is directed outward and downward, and consists of articular and non-articular area.
      • The articular part is divided into lateral and medial part.
      • The non-articular part(accetabular fossa) is cut into its depth by a rough non-articular depression called acetabular notch.
      • Acetabulum is surrounded by a rim to which a ring of fibro-cartilage is attached.
      • It presents three notches; namely: postero-internal (acetabular) notch, antero-internal notch & external notch.
      • The postero-internal notch is deeper and leads into acetabular fossa.
      • The antero-internal and external notches are small and shallow and don’t reach to the acetabular fossa.

      The Obturator Foramen:

      • The obturator foramen is a large oval opening found on the floor of the pelvis and is formed by the ischium and the pubis. 
      • It is the largest foramen of the body.
      • The margin is thin and sharp, except at its external parts.
      • Its long axis is directed outwards and forwards.
      • In the fresh state, the foramen is closed by fibrous membrane, ligaments and muscle ( obturator externus & obturator internus muscles), leaving a narrow space for passage of vessels and nerves.

      DIFFERENCES IN MALE AND FEMALE HIP BONES:

      
      
      Marked differences exist in size and form of the pelvis of the two sexes.
      •  Both transverse diameter ( distance between two psoas tubercles) and conjugate diameter(length between body of sacrum and cranial end of the public symphysis) are greater in female.
      • Inclination of the pelvis towards front, is greater in female.
      • Pelvic outlet and ischial arch are wider in female.
      • The angle made by symphysis ishcii, are greater in female and makes the pelvic cavity roomier in female.
      • The obturator foramina are larger in the female.
      
      
      Comparison with:
      
      
      
      A)    Pelvic Bone of Horse: 
      
      

      
      • The ischium is placed more obliquely.
      • The gluteal line is faint.
      • The nutrient foramen is placed on or near the posterior part of lateral border.
      • The two-ischii meet at a greater angle, rendering the pelvic floor like bowl/basin.
      • The inferior ischiatic spine, which is present only in horse, runs from the under surface of the tuber ischia inward and forward.
      • The acetabulum and acetabular notch is wider than ox. The secondary acetabular notch is absent.
      • The superior ischiatic spine is not so sharp.
      • The tuber ischia is prominent but doesn’t present the trifid process as in ox.
      • The subpubic groove is wider, more extensive and well marked.
      • Psoas tubercle is less developed.
      • The obturator foramen is small.
      
      
      B)    Pelvic Bone of Dog:
      
      

      

      
      
      • The ilium is nearly vertical and iliac shaft is compressed from side to side.
      • The gluteal surface of ilium is more concave and is directed directly outwards.
      • The pelvic surface is nearly flat.
      • The dorsal border is convex, thick and rough.
      • The pubic border is better marked and is continuous.
      • The external angle is undivided.
      • The superior ischiatic spine is low but thick.
      • The greater ischiatic notch is shallow.
      • The lesser ischiatic notch is absent.
      • The ischium has a twisted appearance and ischial arch is very wide.
      • The sub-pubic groove is absent.
      • The acetabulum and acetabular fossa are deep.
      • The acetabular foramen is triangular in outline with the angles rounded off.
      
      
      C)    Pelvic Bone of Pig:
      
      

      
      • Ilium is less extended laterally and dorsal border is convex.
      • Tuber sacrale is inclined caudally.
      • Psoas and pectinal tubercles are prominent.
      • The ischial tuberosity is trifid.
      • Rim of acetabulum is thicker.
      
      
      D)   Pelvic Bone of Goat:
      
      
      The os coxae differ greatly from that of the ox.
      • The long axis of the  ilium is almost in a line with that of ischium.
      • The gluteal line appears as a ridge and is nearly parallel with the lateral border.
      • The tuber coxae is only slightly thickened and tuber sacrale is pointed.
      • The pubis resembles with the ox but its anterior border is thin and sharp.
      • The ischium slopes downward and backward, and forms a much larger angle with its fellow.
      • The lesser schiatic notch is very shallow.
      • The tuber ischii is flattened and everted (same position).
      • The acetabulum is relatively larger and deeper.
      • The floor of the pelvic cavity is wide and shallow as compared with ox.
      
      
      E) Pelvic Bone of Fowl:
      • The ilia are fused with the sacrum,
      • The pubic is long and in the form of thin elongated stick.
      • Acetabulum is perforated.
      • There is extra large aperture called ilio-shciatic foramen, in between the ilium and  ischium.

        GROSS STUDY OF FEMUR (THIGH)    

        

        
        
        
        

        FEMUR

           It is largest and most massive bone in the body.
        
        
        Shape: cylindrical above and prismatic below.
        Direction: It extends obliquely downward and forward.
        Location: This bone is distal to hipbone.
        Artilation: Articulates with acetabulum above forming a hip joint and tibia & patella below forming a femero-tibial and femero-patellar joint.
        
        

        
        
        
        Composition: It presents 1 shaft & 2 extremities.
        
        
        Shaft:
        • It is cylindrical above and prismatic below.
        • It consists of 4 surfaces & 2 borders.     
        Surfaces:
        The anterior, lateral and medial surfaces:
        • They are smooth, convex and continuous with each other and remain covered by quadriceps femoris muscle.
        Posterior surface: 
        
        • It is rough, narrow in middle but wider at the extremities.
        
        
        
        Borders:
        
        
        Medial Border:
        • It bears trochanter minor at the middleao upper-third, which advance to the posterior surface.
        • Trochantor minor presents medially a rough elongated depression, which gives attachment to the common tendon of iliacus and psoas major muscle.
        • Dorsally it gives attachment to quadratus femoris. Immediately below and external to the trochantor minor, linear rough markings intended for the insertion of pectinious muscle. 
        • Below the trochantor minor, there is wide vascular groove running obliquely downward and outward.
        • The distal-third of the medial border, there is small rough obtuse eminence, the medial supracondoyloid crest, which attaches medial head of the gastrocnenemius muscles. 
        Lateral border:
        • At the level of supracondyloid crest, there is an elongated supracondyloid fossa, the other margin of which bears the lateral supracondyloid crest. 
        Extremities:
        
        
        Proximal Extremity:
        •  It is very wide and is composed of a head, neck and trochantor major.
        • Head is placed medially and is directed inwards to articulate with the acetabulum of pelvic bone. 
        • There is small sulcus/fovea capitis at the center of head which attaches round ligament.
        •   Below the head there is constriction, the neck, which is well marked.
        • The tronchantor major is placed laterally and is very massive. Its lateral surface is convex, rough and is covered by tendons of middle & deep gluteus muscles. 
        • The medial surface is concave and forms the lateral boundary of trochanteric fossa.
        • Continuous with the tronchantor major posteriorly and connecting it to the trochantor minor is the trochanteric ridge.
        • Medial to this ridge, is deep trochanteric fossa, in which the common tendon of obturator internus, obturatur externus and gamelli muscles are attached. 
        Distal Extremity:
        • It is large and composed of trochlea in front and two condyles behind.
        •   The trochlea, which articulates with the patella, is slightly oblique and is composed of two ridges or lips separated by a groove called trochlear ridge.
        • The medial ridge is much larger, more prominent and extends higher than the lateral.
        • The rim around the trochlea gives attachment to the capsular ligament of the femuro-tibial articulation.
        • The condyles are medial and lateral, which are separated by deep intercondyloid fossa. 
        • The intercondyloid fossa receives the tibial spine and the cruciate ligament of the femuro-tibial articulation.
        • The lateral condyle is more convex than the medial.
        • Between the lateral condyle and external ridge of the trochlea, there is rough depression called extensor fossa, that gives origin to the peroneous tertius, medial digital extensor and common digital extensor. 
        • Just behind the extensor fossa there is depression marking for the origin of popliteus muscle.
        • The medial condyle presents a tubercle for the attachment of a ligament of femoro-tibial articulation.
        
        
        Comparison with:

        A) Femur of Horse:

        
        • The bone is more massive and posterior surface is wider.
        • On the dorsal third of the lateral border, there is an extra prominence, called trochanter tertius ( Third trochanter), for insertion of superficial gluteus muscle.
        • The trochantor minor is in the form of thick, rough ridge.
        • The supra condyloid crest is better marked and the supra condyloid fossa is deeper.
        • The trochanter major is more massive and is divided into crest, convexity and summit.
        • The head is large and hemispherical. (Shape as half of the earth.)
        • Fovea capitis is deep and notched.
        • Trochanteric ridge is vertical.   

         

        B) Femur of Dog:

        
        • Bone is comparatively larger and the shaft is more curved.
        • The posterior surface is narrow and presents two crest.
        • The trochanter tertius and supracondyloid fossa is absent.
        • There are two supra condyloid crest, the lateral of which is larger.
        • The trochanter minor is like a tuberosity.
        • The tronchanter major is undivided and is lower in level than the head.
        • The head is neatly spherical.
        • The trochanteric fossa is deep and rounded.
        • The trochlear ridges are nearly similar.
        • Each condyle presents at its upper area posteriorly, a small, circular,  slightly concave or nearly flat facet of fabella. 
        • Fabella is small bone and plays the part of sesamoid for the head of the gastrocnemius muscle.
        
        

         

        C) Femur of Pig:

        

        •  Femur is relatively wide and having massive shaft.
        • Supracondyloid fossa and third trochanter is absent.
        • The head is strongly covered and is marked towards the medial side.
        • Neck is distinct.
        • The trochanter major although massive, doesn't extend above the level of head.
        • Trochlear ridge are of similar size.

        D) Femur of Goat:

        • The shaft of femur is slightly curved and the convexity being anterior.
        • A distinct line separates the lateral and posterior surface.
        • The supracondyloid fossa is very shallow.
        • The head has shallow fovea capitis and neck is distinct.
        • The trochanter major is little higher than the head.
        • The ridges of the trochlea are similar and parallel but slightly oblique.

        E) Femur of Fowl:

        • Femur is short and somewhat bent.
        • The head is smaller than the acetabulum.
        • The distal extremity has a deep pulley-like articular area for articulation with the tibia and fibula.
        
        

          THE PATELLA

        It is small, irregularly triangular sesamoid bone. It corresponds to the knee cap of the human.
        It is also considered as a largest sesamoid bone. 
        
        
        Shape: Roughly triangular shape.
        Location: Bone is placed in front of the femoral trochlea.
        Direction: Nearly straight from above downwards.
        Articulation: It articulates with the femoral trochlea below forming a femero-patellar joint.
        Relation: It is attached to the tibia by three extremely strong ligamentous bands(medial, middle & lateral) and placed in front of the femoral trochlea.
        
        

        
        
        
        Composition: It consists of 2 surfaces, 3 borders, 3 angles; a base and an apex.
        
        
        Surfaces:
        
        
        Posterior /articular Surface:
        • Smooth and is divided by a vertical ridge into two areas which articulates with corresponding groove of trochlea.
        Anterior Surface:
        • It is irregularly convex and rough for muscular and ligamentous attachment.
        
        
        Borders:
        • They are medial & lateral, which converge below, to form the apex, which points downward.
        • The dorsal border is somewhat rough and tuberous for the attachment of three patellar ligaments.
        Angles:
        
        
        Lateral Angle:
        • It is formed by the union of base and the lateral border.
        Medial Angle: 
        • Formed by the union of the base and the medial border and gives attachment to the fibro-cartilage of the patella.
        Ventral Angle:
        •   It is formed by the union of medial and lateral border.
        
        
        Base:
        • It is dorsal looks upward and backward and is irregularly convex and rough.
         Apex:
        • Apex is somewhat pointed and is formed by the medial & lateral border, which converge below, pointing downward.
        
        Comparison with:
        
        
        
        A) Patella of Horse
        • Patella is wider and longer.
        • Shape is not as triangular as ox due to blunt apex.
        • Both medial and lateral borders join at base at greater angle.  
        B) Patella of Dog:
        • Patella is long and narrow, nearly oval in outline.
        • Apex is rounded and base is very narrow.
        • Anterior surface is more convex.
        C) Patella of Pig:
        • Patella is much more compressed transversely and presents three surfaces. 
        D) Patella of Goat:
        • Smaller in size, relatively longer and narrower than that of ox. 
        E) Patella of Fowl:
        • Patella is wide and thin.

        • GROSS STUDY OF TIBIA-FIBULA(LEG)                

          
          
          
          

          THE TIBIA(OX)

          Type: It is long and massive bone.
          Shape: It is distinctly curved; three sided above and smaller & flattened below.
          Direction: Placed obliquely downward and backward.
          Relation: It is related with the the femur above and tarsus below.
          Articulation: It articulates proximally with the distal extrimity of femur forming a stiffle joint and distally with tarsal bones forming a hock joint.
          Location: Present in hind limb at leg position.
          
          
          
          
          
          
          
          Composition: 1 shaft & 2 extremities.
          
          
          Shaft:
          
          
               It presents 3 surfaces & 3 borders.
           
          
          
          Surfaces:
          
          
          Lateral surface:
          • It is slightly spiral in its direction.
          • The surface is concave above, convex in middle and nearly flat below.
          • Lodges tibialis anterior muscle. 
          Posterior Surface:
          • It is flattened from side to side.
          • Towards the medial border there is a narrow triangular area for the insertion of the popliteus muscle.
          • The remaining part of this surface is marked by a number of rough lines, the linea muscularis, which serve for the origin of flexor muscle. 
          Medial Surface:
          • It is slightly convex.
          • It is rough at upper part for the attachment of sartorious, gracilis and semi-membranous muscles and medial ligament of the femor-tibial articulation.
          • Below it is narrower, smooth and subcutaneously placed.
          
          
          Borders:
          
          
          Anterior Border:
          •  It is very prominent in upper third and constitutes the tibial crest.
          • The rest of its extent is rounded and indistinct.
          • The crest, at its extent is rounded and indistinct.
          • The crest, at its medial aspect, presents a rough prominence for the insertion of semitendinosous and a part of biceps femoris. 
          Lateral Border:
          • It is concave lengthwise.
          • There is a space between fibrous cord and the lateral border of the tibia, through which anterior tibial vessel passes outward and forward. 
          Medial Border:
          •  It is thicker and rounded in its dorsal half and gives attachment to the popliteus muscle.
          Extremities:
          
          
          Proximal Extremity:
          •  It is large and consists of 3 tuberosities and 2 condyles.
          • The anterior tuberosity is non-articular prominence placed in front of the proximal extremity.
          • It continues below with the tibial crest and gives attachment to the three straight ligaments of patella.
          • Between anterior tuberosity and lateral condyle, there is a deep, smooth semicircular notch called sulculus muscularis, for the passage of common tendon of the proneus tertius, common digital extensor and medial digital extensor.
          • The condyles are medial and lateral, and they stand on top of the medial and lateral tuberosities.
          • Each condyles is swaddle-shaped articular surface, which is prolonged on the spine for articulation with the corresponding condyle of the femur, through the medium of an inter-articular fibro-cartilage.
          • The three tuberosities are separated by inter tuberal fossa.
          • The tibial spine is a central articular eminence divided into a medial higher and lateral lower part.
          • The rudimentary fibula is attached to the lateral tuberosity.
          
          
          Distal Extremity:
          • It is much smaller than the proximal extrimity and articulates with the tibial and fibular tarsal.
          • The surface is compounded of two deep antero-posterior grooves separated by an articular ridge.
          • The medial groove is bounded by the medial malleolus, while the lateral groove is separated by a sharp border which articulates with the lateral malleolus.
          • The anterior part of the medial malleolus is prolonged downward and is pointed. 
          • The lateral malleolus is a separate piece of bone which articulates with the tibia to complete the lateral groove. 
          • This small piece of bone is placed between the proximal ends of the tibial tarsal and the distal end of the fibular tarsal at their lateral aspect.
          Comparison with:
          
          
          A) Tibia of Horse:
          
          
          
          •  Comparatively larger and longer.
          • Ridges on posterior surface are more.
          • The posterior surface is divided into two by an oblique popliteal line.
          •   Nutrient foramen is either on or near to the popliteal line.
          • The anterior tuberosity is vertically grooved.
          •   Sulcus muscularis is wider.
          • There is a face on outerside of the lateral tuberosity for the articulation with the fibula
          • The grooves and ridge on the distal extremity are directed obliquely downward and outward.
          • The lateral groove is wider but shallower than the medial.
          • The lateral malleolus is not a separate piece but is wider than that of ox while the medial malleolus is more prominent of the two.
          
          
          B) Tibia of Dog:
          
          
          
          • Tibia is as long as the fibula.
          • Shaft forms a double curve, the proximal part is convex medially and distal part is convex laterally.
          • The tibial crest is more prominent but short.
          • Nutrient foramen is usually found in the upper third of the lateral border.
          • The anterior tuberosity is not grooved.
          • The distal extremity is small and four sided.
          • The lateral malleolus is not fused with the distal extremity.
          
          
          C) Tibia of Pig:
          
          
          
          
          •  More similar with than that of ox.
          • The tuberosity is grooved in front, and a narrow sulcus separates it from lateral condyle.
          • The posterior part of the crest is very prominent and curves outwards.
          • The sulcus is narrow.
          • It presents a proximal and distal facet for articulation with the fibula at lateral aspect.
          
          
          D) Tibia of Goat:
          • It is long and slender, but otherwise resembles to that of ox.
          
          
          E) Tibia of Fowl:
          
          
          
           Fig: The skeleton of fowl showing tibia fibula
          
          
            30. Fibula, 31. Tibia, 32. Metatarsus
          
          
          
          
          
          
          • The tibia in reality is tibio-tarsus because the bone of the proximal row of the tarsus are fused with the distal end of tibia.
          •   Shaft is nearly straight.
          • Tibial crest is prominent.
          • Distal end is condyloid.
          • This is the largest bone of the body.
          
          
                   THE FIBULA
          • The fibula is rudimentary bone.
          • In young it is in the form of fibrous cord extending from the lateral tuberosity of the  tibia to the lateral maleolus.
          • In adult, the proximal end of this fibrous cord becomes ossified, and the head of the fibula is fused with lateral tuberosity of tibia.
          • The distal extremity also ossifies but remains separate as the lateral maleolus.
          • The body later gets reduced to a small, short blunt and elongated prolongation of the fibrous cord.
          • The body and the distal end remain as the blunt prolongation.
          
          
          Comparison with:
          
          
          A) Fibula of Horse:
          • Better developed than in the ox.
          • It is an aborted long bone and looks like a splint bone.
          • It presents a body and two extremities.
          • Fibula is placed along the lateral border of tibia.
          • Proximal extremity or the head is the thickest portion of the bone.
          • Distal extremity forms a sharp pointed end and terminates in the lower third of the tibia.
          • Anterior and posterior borders are thick and blunt.
          
          
          B) Fibula of Dog:
          • Fibula is as long as tibia and is slender, slightly twisted and larger at either extremities.
          • The proximal part of the shaft is separated form the tibia by a large interosseous space, but the middle and the lower parts are flattened and closely attached to the tibia by interosseous ligament. 
          • The distal extremity forms the lateral maleolus which articulates with the tibia and the tibial tarsal medially.
            
          
          
          C) Fibula of Pig:
          •  Fibula is thin bone and extends the entire length of tibia, separated by a wide interosseous space.
          • The shaft is flattened from side to side.
          • The proximal part is wide and deeply grooved laterally.
          • The distal part is narrower and thicker.
          
          
          D) Fibula of Goat:
          • The fibula has no shaft, and its proximal end is represented by small prominence below the lateral margin of the lateral tuberosity of the tibia.
          • The distal end forms the lateral maleolus, as in the ox.
           
          
          E) Fibula of Fowl:
          • Fibula is much reduced long bone.
          • The articular head is massive and is flattened from side to side.
          • The body is slender and tapers to a point one-half way down the tibia. 

          1. goog_1733926908

        1. ·     The cranial end is flat and the caudal one is divided into a dorsal and goog_1733926909
      • The proximal extrimity is enlarged and is flattened transversally. It articulates with the lateral condyles of the femur and tibia.
      • 
        

        GROSS STUDY OF TARSUS  

        Bones of the Pes
        

        

        Pes is the fourth segment of hindlimb/pelvic limb

        It consists of three segments;

        • Tarsus- consists of tarsal bones
        • Metatarsus- consists of metatarsal bones
        • Digit/digits- consists of phalanges and sesamoid bones

        General plan for Tarsus (in domestic animals and birds) 

        • A group of tarsal bones are known as tarsus.
        • Tarsus is the first segment of pes.
        • Tarsus consists of number of bones ranging from five to seven tarsal bones in domestic animals and in adult fowl the tarsus do not exist .
        • These bones are arranged in three rows; i.e., proximal, central and distal row.
        • The proximal row consists of two tarsal bones and are arranged from medial to lateral as tibial tarsal, and fibular tarsal.
        • The central row consists of only one bone except ox where it is fused with 4th tarsal bone. 
        • The distal row consists of two to four tarsal bones and are arranged in the same manner as first, second, third, and fourth tarsal bones except ox where first tarsal is on the lateral side.
        • In case of fowl, the tarsus in the adult chicken does not consists of a group of small bones as in mammals. During fetal life the tarsus bone do exist in the two rows. The proximal row fuses with the tibia and the distal row fuses with the metatarsus.

        Tarsus(ox)
        

        • It is the first section of the pes and consists of five short bones, arranged in three rows; proximal, central and distal.
        • The bones of tarsus are arranged between the tibia/fibula above and metatarsal bones below forming a hock joint.
        • The bones of the proximal row (from medial to lateral) are: tibial tarsal(astragalus), fibular tarsal(os-calsis).
        • Bones of the central row are: central & fourth fused tarsal(scaphocuboid).
        • Bones of the distal row are: 2nd and 3rd fused tarsal(cuneiform magnum) on the medial side and 1st tarsal(cuneiform parvum) on the lateral side.

        

        
        

        TIBIAL TARSAL:

        • It is the medial bone of the proximal row and is somewhat compressed from before backwards.
        • It has 6 surfaces.
        • The dorsal and anterior surfaces are continuous and are articular. It is trochlear in appearance and articulates with the distal extremity of the tibia. A deep fossa is present at the anterior surface.
        • The posterior surface is smooth and articulates with the fibular tarsal.
        • The medial surface is slightly depressed, nearly flat about its middle, and marks a small tubercle above the depression.
        • The lateral surface is irregularly concave and articular.
        • The ventral surface articulates with central & 4th tarsal, and is composed of two condyles separated by a groove.

        Relations:

        • Articulates proximally & anteriorly with the tibia.
        • Articulates antero-laterally with the lateral maleolus.
        • Articulates posteriorly with fibular tarsal.
        • Articulates distally with central & 4th tarsal.
        • Articulates laterally with a part of fibular tarsal.

        FIBULAR TARSAL:

        • It is largest bone of the tarsus.
        • It is elongated and flattened from side to side and is placed behind and lateral to the tibial tarsal.
        • The body or the middle part is flat, the medial surface of which is slightly concave and lateral surface convex.
        • The posterior border is nearly straight and gives attachment to planter ligament.
        • The anterior ligament is slightly concave, smooth and rounded.
        • The proximal extremity(tuber calcis) forms the point of hock and presents a depression for insertion of gastrocnmius tendon.
        • Ventral extremity is irregular.
        • Medially a strong, thick projection articulates with the posterior surface of tibial tarsal, known as sustentaculum tail.

        Relations:

        • Articulates anteriorly with the tibial tarsal.
        • Articulates ventrally with a part of central & 4th tarsal.
        • Articulates medially with the lateral surface of tibial tarsal.
        • Articulates dorsally with the lateral maleolus.

        CENTRAL & FOURTH FUSED TARSAL:

        • The central and 4th tarsals are fused together to form a large single bone, which occupies the entire width of the tarsus and articulates with the bones of the joint.
        • Dorsal surface is concave and smooth. There is spine at postero-medial angle of this surface.
        • The ventral surface has two different levels for fusion with 4th tarsal bone.
        • The anterior and the medial surfaces are continuous, convex and rough.
        • The lateral surface is very uneven and rough.
        • The posterior surface is irregular and presents two tubercles ( lateral & medial).

        Relations:

        • Articulates superiorly with tibial & fibular tarsal.
        • Articulates inferiorly with 2nd & 3rd fused tarsal and large metatarsal.
        • Articulates posteriorly with 1st tarsal.

        FIRST TARSAL:

        It is quadrilateral piece of bone placed at the postero-internal part of the tarsus.

        Relations:

        • Articulates dorsally with central & 4th tarsal fused.
        • Articulates ventrally with large metatarsal bone.
        • Articulates anteriorly with 2nd & 3rd tarsal fused.

        SECOND & THIRD TARSAL FUSED:

        • It is small, flattened plate of bone placed under the ventral surface of central & 4th fused tarsal.
        • Dorsal surface is concave and articulates with the medial part of the ventral surface of the central & 4th fused tarsal.
        • Ventral surface is concavo-convex and articulates with medial facet on the proximal articular surface of the large metatarsal.
        • The anterior and medial surfaces are continuous, convex, rough and non-articular.
        • Lateral surface has small facet in front for articulation with central & 4th fused tarsal.
        • Posterior surface is narrow and has small facet for articulation with 1st tarsal.

        Comparison with:

        A) Tarsus of Horse:

        • It has 6 tarsal bones, namely: tibial, fibular, central, first & second fused, third and fourth tarsal.
        • Tibial and fibular tarsal bones are shorter and thicker.
        • Sustentaculum tali are stronger, longer and bear a facet in front of tibial tarsal.
        • Central and third tarsal bones are flat in shape.
        • First and second fused bone is small.
        • Fourth tarsal bone is irregular.

        

        
        

        

        
        

        B) Tarsus of Dog:

        • 7 tarsal bones namely: tibial, fibular, central, first, second, third and fourth tarsal bones.
        • Tibial tarsal has body, neck and head.
        • Fibula tarsal is elongated and has a long process in front forming the beak.
        • Sustantaculum tail are short and small.
        • Central tarsal is concave above for articulation with head of tibial tarsal.
        • First tarsal is irregularly quadrilateral and flat.
        • Second tarsal is smallest bone of tarsus and is wedge shaped.
        • Third tarsus is also wedge shaped.
        • Fourth tarsus is very high and four sided.

        

        
        

        C) Tarsus of Pig:

        • Tarsal bones are seven in number as in dog.
        • Tibial and fibular tarsal are similar in shape to that of ox.
        • Second tarsal is small.
        • Third and fourth are larger.

        

        
        

        D) Tarsus of Rabbit:

        • Tarsus bones are arranged in three rows.
        • Proximal row ( two bones): Tibial and fibular tarsal.
        • Middle row: central tarsal.
        • Distal row (three bones): first & second fused, third and fourth tarsal.

        E) Tarsus of Fowl:

        • Tarsus appears to be absent in adult fowl.
        • The proximal row unites with the tibia called tibio-tarsus.
        • The distal row fused with metatarsus to form tarso-metatarsus.

         STUDY OF METATARSUS & DIGIT/DIGITS

         Bones of the Pes

        • 

          
          

          
          
          
          
          Pes is the fourth segment of hindlimb/pelvic limb
          It consists of three segments;
          

          • Tarsus-consists of carpal bones
          • Metatarsus-consists of metacarpal bones
          • Digit/digits-consists of phalanges and sesamoid bones 

          General plan for metatarsus (in domestic animals and birds)
          

          • A group of metatarsal bones are known as metatarsus.
          • Metatarsus is the second segment of pes and is located between tarsus above and digit/digits below.
          • Metatarsus in general, resembles, those of corrosponding regions of the fore limb/thoracic limb with some differential features noted in species comparision.
          • Metatarsus consists of number of bones ranging from three to five metatarsal bones in domestic animals and birds.
          • They are long bones and are arranged numerically from medial to lateral as first, second, third, fourth, and fifth (I, II, III, IV, V).
          • Such arrangement mainly occurs in dog, although the first metatarsal is much smaller than the others and the second and fifth are somewhat reduced where the third and fourth metatarsals are well developed that carry the chief digits.
          • In the ox, first and fifth metatarsals are absent, the third and fourth are well developed metatarsals that carry the well developed digits; they are fused in the ox, sheep/goat. The second one is quadrilateral disc like located at medioplanter angle of the proximal end of third metatarsal bone.
          • In the horse, first and fifth metatarsals are absent, the third one is well developed and carries a single digit, where as the second and fourth are much reduced.
          • In the pig, first metatarsal is absent, the third and fourth metatarsals are well developed that carry the chief digits where the second and fifth are somewhat reduced and carry accessory digit.
          •  In the fowl, four metatarsal bones are present where first one is very small. The second, third, and fourth are elongated and carry a chief digit. 

        METATARSUS(OX)

        • The metatarsus of ox consists of  three metacarpal bones (II, III, IV). Of which third one is located on the medial side and the fourth one is located on the lateral side during fetal life, but later becomes fused forming a large metatarsal bone. There is a medial small rudimentary second metatarsal bone.
          

          

          
          
          THE LARGE METATARSAL BONE:
          This resembles to the large metacarpal but differs from it as;
          

          • The large metatarsal bone (III and IV) is about one-seventh longer than the   corresponding metacarpal.
          • Metatarsal is larger and distinctly quadrilateral in form.
          • Shaft is compressed transversely, and is distinctly four sided.
          • The vascular groove on anterior surface is wider and deeper.
          • The foramen at proximal part of this surface doesn't pass through the shaft but runs obliquely through the extrimity and opens on the planter part of its proximal surface.
          • The dorsal longitudinal sulcus is deep and wide.
          • The planter surface is marked by variable grooves.
          • The medial surface is flat and wide above. 
          • The distal extremity is slightly narrower than metacarpal bone. 
          • Proximal end bears a facet at its medial aspect for small metatarsal bone.
          
          
          The SMALL METATARSAL BONE:
          • It is medially situated, quadrilateral and disc like bone about 2cm in width and height.
          • It is rudimentary bone.
          • Its dorsal surface bears a facet for articulation with large metatarsal bone.
          • It may be a sesamoid bone, and regarded as metatarsal sesamoid bone. 
          
          
          
          Comparison with:
          A) Metatarsal of Horse:
          
          

          

          
           
          THE LARGE METATARSAL BONE:
          
           The metatarsus of horse consists of three metacarpal bones (II, III, and IV) and have the same general arrangement as the metacarpal bones, but differs in some aspects as;
          

          • Their direction is slightly oblique, distal and a little dorsal.
          • The third or large metatarsal bone is about one-sixth longer than the corresponding metacarpal; in median size animal the difference is about 5cm.
          • The body or shaft is more cylindrical and is almost circular on cross section, except in its distal part.
          • At the proximal part of its lateral surface there is a groove which is directed obliquely distally and plantarly and is continued by the furrow formed by the fourth metatarsal bone.
          • The nutrient foramen is relatively higher than on the metacarpal bone   
          • Vascular groove is absent.
          • Proximal extremity is wider and much greater than that of the metacarpal bone.
          • Its articular surface is slightly concave and is marked by a large, central, non-articular depression, continued laterally by a deep notch.
          THE SMALL METATARSAL BONE:
          

          •  The second and fourth  small metararsal bones are a little longer than the corresponding metacarpals.
          • The fourth metatarsal bone is relativelt massive, specially on its proximal part.
          • The base or  proximal extrimity is large and bears one or two facets proximally for the fourth tarsal and two dorsomedially for articulation with the large metatarsal.
          • The second metatarsal bone is much more slender than the fourth, specially towards its base.
          •  Proximally it bears two facets for the fused first and second tarsals, sometimes one for the third tarsal and dorsolaterally, two facets for the third metatarsal. 
          
          
          B) Metatarsal of Dog:
          
          

          

          
          
          
          
           The metatarsus of dog consists of five metacarpal bones (I, II, III, IV, and V) and have the same general arrangement as the metacarpal bones, but differs in some aspects as;
          • First metatarsal is very small and pea like, somewhat compressed laterally.
          • It articulates with the first tarsal
          • Third and fourth  metatarsals are nearly equal in length being slightly larger than the second and fifth.
          • Third and fourth  metatarsals have facets for articulation with two small, rounded sesamoid bones.
          • The second is slightly longer or equal to the fifth metatarsal bones. 
          C) Metatarsal of Pig:
          

          

          
          
           The metatarsus of pig consists of four metacarpal bones (II, III, IV, and V) and have the same general arrangement as the metacarpal bones, but differs in some aspects as;
          •      The metatarsal bones are somewhat longer.
          •      The proximal ends of the third and fourth metatarsals have a conciderable planter projection.
          •      The process on the third metatarsal has a facet for articulation with a discoid metatarsal sesamoid bone.
          •      The second and fifth are placed more towards the planter aspect of the third and fourth than in the fore limb.
          D) Metatarsal of Rabbit:
          •  Four metatarsals are present.
          • They are narrow rod shaped structures.
          • First digit is absent and rest digits have three phalanges.
          E) Metatarsal of Fowl:
          
          

          

          
          
          The metatarsus consists of four metacarpal bones (I, II, III, and IV) and differ widely in the  arrangement compare to metacarpal bones as;
          

          • The first metatarsus is very small
            
          • In adult the tarso-metatarsus is represented by a single long bone resulting from the fusion of 3 bones ( 2nd, 3rd & 4th metatarsus).
          • The proximal extremity is compounded with tarsus, and is very irregular and has two concavities for articulation with tibia.
          • The distal extremity is divided into three articular projections, which supports three principal digits.
          • In the male, there is a conical, slightly curved projection at the distal third, which serves as support for horny spur. 
          
           DIGIT/DIGITS OF HIND LIMB
          

          • Digit/digits are the third segment of pes.
          • It consists of phalanges and sesamoid bones.
          • digital bones in general, resembles, those of corrosponding regions of the forelimb/thoracic limb with some differential features noted in species comparision.

          
          DIGITS (OX)
          

          • The digits of hindlimb/pelvic limb resembles those of forelimb/thoracic limb very closely except in their dimension and inclination. 
          • It is very difficult to make a difference in ruminants. so, the separate description is not necessary.
          • Sesamoid bones are similar with that of forelimb.

          
          DIGIT (HORSE)
          

          • The axis of the phalanges of the hind limb forms an angle which is about five degree greater  than the fore limb.
          • The major differences in the form and size of the bones are as follows;

          First phalanx
          

          • The first phalanx is little shorter, wider proximally and narrower distally.

          Second phalanx
          

          • The second phalanx is narrower and slightly longer.

          Third phalanx
          

          • The distal phalanx is narrower.
          • The planter surface is more concave.
          • The planter processes are less prominent and closer together.

          Sesamoid bones
          

          •  The proximal sesamoid bones are little smaller, except in thickness.
          •  The distal sesamoid bone is narrower and shorter.

          DIGITS (DOG)
          

          • The first digit is often absent. If present, its development varies and it may contains either one or two phalanges.
          • In other cases, specially in very large dogs, a sixth digit is also present; it does not articulate with the metatarsus, but attached with fibrous tissue.
          • The other digits except first resemble those of forelimb.
          • Sesamoid bones are similar with that of forelimb.

           DIGITS (PIG)
          

          •  The first and second phalanges of each digit are coparatively longer and narrower than those of the forelimb.
          • Sesamoid bones are similar with that of forelimb.

          DIGITS (FOWL)
          

          • The digits of fowl varies greatly in form, size and number.
          • The digits of fowl are four in number, arranged numerically as (I, II, III, IV)
            
          • The first digit(the hallux) is very small which is posteriorly directed toe consists of two phalanges.
          • Digits second,third, and fourth are located numerically from medial to lateral to their respective trochleae and consists of three, four, and five phalanges respectively.
          • The third phalanx of each digit is a claw which is covered by horny structure exteriorly.

        The Axial Skeleton | Gross Anatomy | Anjani Mishra

        

        
        
        

        THE AXIAL SKELETON

        The axial skeleton is the branch of skeleton which deals with the bones of the head, vertebral column, ribs and sternum.

        
        

        BONES OF THE HEAD

        
        

        

        
        

        THE SKULL BONES                  

        The skull provides a means of the protection for the brain, the organs of special senses (sight, smell, hearing, equilibrium and taste), the openings for the passages of air and food, and the jaws, including the teeth for mastication. The term ‘‘cranium’’ (bones of the skull) is sometimes referred to as consisting of those bones which lodge and protect the brain devoid of the mandible and facial bones. According to the Nomina  Anatomica  Veterinaria  (NAV);1968  divides the skull in to 2 groups namely:-

         

        ·        Bones of the cranium &

        ·        Bones of the face

           # Formula to remember paired and single bones of skull

        
           @ SHEVOM- Single bones
           @ all the rest- paired bones
        
          # Formula to separate cranial and facial bones of skull

         
          @ SOFTPIE- Cranial bones
          @ all the rest- facial bones

        CRANIAL BONES(paired)

        Parietal Bone:-

        The parietal bone is a paired structure and forms the dorsolateral wall of the cranium with the cccipital bone caudally and the frontal bone rostrally. It is composed of a parietal plane, temporal plane and a nuchal plane (in the ox). Internally the grooves and ridges correspond with the gyri and sulci of the brain. There is also an interparietal bone between the occipital bone and the parietal bone which fuses with age.

        Interparietal:-

        The interparietal bones are a median bone situated between the squamous part of the occipital bone and the parietal bone. The bones of either side fuse with each other and with the parietal bone.

        Frontal Bone:-

        The frontal bone is a paired structure joined by the interfrontal suture between the cranium and the face and enclosing the frontal sinuses. The nasal and lacrimal bones border the frontal squama section and form the zygomatic process laterally and part of the orbit dorsally. Lacrimal glands are also present near the orbit. The temporal line extends into the external sagittal crest.

        Temporal Bone :-
        The temporal bone is composed of squamous, petrosal and tympanic parts and forms the lateral wall of the cranial cavity. It articulates with the frontal, parietal and sphenoid bones. The squamous element joins the temporal process of the zygomatic bone to form the zygomatic arch and forms the articulating surface of the temporomandibular joint. An articular tubercle and mandibular fossa are present.

        

        
        
        

        
        

        
        

        CRANIAL BONES(unpaired)

        Occipital Bone:-

        The occipital bone forms the nuchal wall and the foramen magnum. The pars basilaris element is the caudal base of the cranium, although rostral to foramen magnum and joined by a cartilaginous suture to basisphenoid bone. A nuchal crest is present and is easily palpable. The nuchal crest is often used as a landmark for collection of cerebrospinal fluid (CSF). There are also external occipital protuberances present which provide muscle attachment sites for the nuchal ligament. The lateral parts form the borders of foramen magnum. Occipital condyles are present which articulate with the atlas to form the atlanto-occipital joint. The paracondylar process provide muscle attachment sites for muscles of the head. The hypoglossal canal is also within this structure.

        Sphenoid Bone:-

        The sphenoid bone forms the base of the neurocranium and is composed of a body and wings. The bones are separated by cartilage which ossifies with age. The presphenoid is rostral and has a caudal fossa which is a hollow body with sphenoid sinuses located inside. The pterygoid processes and oval foramen are also present in this structure.

        Ethmoid Bone:-

        The ethmoid bone forms part of the cranial and facial parts of the skull and is located deep in the orbit. External lamina consist of the roof plate, floor plate and paired orbital plates. The ethmoid bone is separated from the cranial cavity by the cribriform plate. Numerous small foramina exist where the olfactory nerve (CN I) passes through. The perpendicular plate splits the ethmoid into two halves and the ethmoid larbyrinth protrudes from the ethmoid tubes. The tubes are composed of two rows of ethmoturbinates and air filled ethmoidal meatuses. Secondary ethmoturbinates may also be present. Ethmoturbinates are divided into endoturbinates and ectoturbinates. The first endoturbinate forms the dorsal nasal conchae and the second endoturbinate froms the middle nasal conchae. The endoturbinates form 3 nasal meatuses; the dorsal nasal meatus, the middle nasal meatus and the ventral nasal meatus.

         

        

        
        

        

        
        
        

        

        
        
        

        FACIAL BONES(paired)
        
        Maxilla:-

        The maxilla forms most of the facial part of the skull, including the lateral walls of the face, nasal cavity, oral cavity and hard palate. It also forms the ventral nasal conchae and articulates with all of the facial bones as it is the largest bone of the face.

        Premaxilla:-

        The premaxilla (incisive) bones are the most rostral bone of the face and are each composed of a body, a palatine process and a nasal process. The bone is narrower and more pointed rostrally in case of ox.

        Lacrimal:-

        The lacrimal bone forms part of the lateral wall of the face and orbit and is situated near the medial canthus. It articulates with the frontal bone, zygomatic bone and maxilla. It also articulates with the nasal bone in ruminants and the horse and articulates with the palatine bone in carnivores. It is composed of an orbital and facial part separated by supra- and infraorbital margins. The nasolacrimal duct is present by the margin of the orbital surface. The ventral oblique muscle attaches caudal to the margin of the orbital surface. The nasal surface forms the boundaries of the maxillary and frontal sinuses.

        Malar/Zygomatic:-

        The molar (zygomatic) bone is in the caudolateral area of the face and forms the ventral border of the orbital cavity.

        Pterygoid:-

        The pterygoid bone is a paired structure bordered by the palatine and sphenoid bones. It forms the dorsal and lateral walls of the nasopharyngeal cavity. The pterygoid hamulus is formed by the pterygoid bone.

        Nasal:-

        The nasal bone is a paired structure and forms the roof of the nasal cavity. Dorsal nasal conchae attach to the ethmoidal crest on the internal surface. A rostral suture forms the apex and between the nasal and incisive bones is the naso-incisive notch.

        Palatine:-

        The palatine bone is a paired structure between the maxilla, sphenoid and pterygoid bones. It is composed of horizontal plate(forms part of the hard palate) on which nasal crest is present. The palatine sinus is present on horizontal plate.

        Turbinate bones:-

        These are delicate, scroll-like bones(four in number) which are attached to the lateral wall of the nasal cavity. Each bone is composed of a very thin lamina, cribriform in many places and covered on both sides with mucous membrane in the fresh state. They are arranged in two pairs, dorsal and ventral.

         

        

        
        

        
        

        FACIAL BONES(unpaired)

        Vomer:-

        The vomer is unpaired and extends from the choanae of the palatine bone to the floor of the nasal cavity. It attaches to the median nuchal crest and has a septal sulcus which surrounds nasal cavity.

        Mandible:-

        The mandible can be divided into the body and the ramus. The body of the mandible supports the incisor teeth (rostrally) and cheek teeth (caudally). The section of the body which does not support any teeth is called the inter-alveolar margin or diastema. The mandible also contains the mandibular canal and the mental foramen. The facial notch is on the ventral surface where the parotid duct (in herbivores) and facial vessels run. The ramus extends from the caudal end of the body dorsally towards the zygomatic arch.  The condylar process articulates with the mandibular process of the skull.

        

        
        
        

        Here, we see the bones of skull are flat bones, developed in membrane and the bones of the cranial base may be classed as irregular and are developed in cartilage . Only two form are permanent movable joints with other part of skull .The mandible form synovial joint with the temporal bone, and the hyoid bone is attached to the latter by bar of cartilage. The immovable joint located between most of the bones of skull are termed ‘suture’. But these suture disappear by osseous fusion on increasing age of animal. The skull present numerous foramina as mention below: - infraorbital, mental, mandibular, supraorbital, etc. through which cranial nerves and blood vessels enter and exit.

        
        

        Hyoid Bone:-

        ·     The hyoid bone(Os hyoidiun) is situated chiefly between the vertical parts of the rami of the mandible, but its upper part extends somewhat further back.

        ·     It is attached to the petrous temporal bones by rods of cartilage, and supports the root of the tongue, the pharynx, and the larynx.

         It consists of a body, a lingual process, and the four pairs of cornua.

        Body:

        ·     The body is a short transverse bar, compressed dorso-ventrally.

        ·     The dorsal surface is concave and smooth in its middle, and presents a convex facet or tubercle at each end for articulation with the small cornu.

        ·     The ventral surface is flattened and is slightly roughened for muscular attachment.

        ·     The anterior border carries the lingual process medially.

        ·     The posterior border is concave and smooth in its middle and carries the thyroid cornu on either side.

        Lingual process:

        ·      It has a short tuberous lingual process.

        ·      The lingual process projects forward medially from the body, and is embedded in the root of the tongue.

        Cornua:

        A.    The thyroid cornua or thyroids

        ·     They extend backward and upward from the lateral parts of the body.

        ·     They are compressed laterally(except at their junction with the body), and the posterior end has a short cartilaginous prolongation which is connected with the anterior cornu of the thyroid cartilage of larynx.

        B.    The small cornua or keratohyoids

        ·     They are short rods which are directed upward and forward from either end of the body.

        ·     Each of which is somewhat constricted in its middle part and has a slightly enlarged ends.

        ·     The ventral end has a small concave facet which articulates with the body.

        ·     The dorsal end articulates with the great cornu(horse), or with the middle cornu when present.

        C.    The middle cornua or epihyoids

        ·     These are small, wedge-shaped pieces or nodules interposed between the small and great cornua.

        ·     They are usually transitory, and unite with the great cornua in the adult.

        ·     The middle cornua are almost as large as the small cornua.

        D.     The great cornua or stylohyoids

        ·     They are the largest parts of the bone.

        ·     They are directed dorsally and backward, and are connected above with the base of the petrous temporal bone.

        ·     Each of which is a thin plate, which is slightly curved in its length, so that the lateral surface is concave and the medial surface is convex. Both surfaces are smooth.

        ·     The border are thin. The dorsal extremity is large and forms two angles; the articular angle is connected by a rod of cartilage with the hyoid process of the petrous temporal bone whereas the muscular angle is somewhat thickened and rough for muscular attachment.

        ·     The ventral extremity is small, and articulates with the small or middle cornu.

        
        

        

        
        

        
        

        

        
        

        
        

        THE VERTEBRAL COLUMN

        
        

        • It is the part of axial skeleton.
        • It is an articulated structure of vertebra, cartilage and ligaments that gives passage to the spinal cord and its covering(meninges).
        • Commonly called spine of the body.
        • It comprises of five regions:

        Vertebra	Region
        Cervical Thoracic or Dorsal Lumbar Sacral Coccygeal	Neck Withers & back Loin Croup Tail

        
        Definition:

        Vertebral column is the fundamental part of axial skeleton consists of chain of median, unpaired, and irregular bones which extends from the occipital bone to the end of the tail.

        The vertebral column is subdivided for description into 5 regions, which are named A/to the part of the body in which the vertebrae are situated. Thus the vertebrae are designated as cervical, thoracic, lumbar, sacral and coccygeal(caudal) vertebrae. The number of vertebrae in a given species is fairly constant in each region except the last, so that the vertebral formula may be expressed(for example in case of ox) as follows;

        OX- C7, T13 , L6, S5, Cy18-20

        Vertebral formula- express the total number of bones present in the vertebral column.

        Vertebral formula of domestic animals and fowl:

        
        

        Species	Cervical	Thoracic	Lumbar	Sacral	Coccygeal	Total(Av.)
        Ox	C7	T13	L6	S5	Cy18-20	50
        Horse	C7	T18	L6	S5	Cy15-21	54
        Sheep/Goat	C7	T13	L6-7	S4	Cy16-18	48
        Dog	C7	T13	L7	S3	Cy20-23	51
        Pig	C7	T14-15	L6-7	S4	Cy20-23	53
        Fowl	C14	T7	(L+S)14		Cy6	41

        
        TYPICAL VERTEBRA:

        
        

                    The vertebrae in a given region have characteristics by which they may be distinguished from those of other regions, and individual vertebra have characteristics which are more or less clearly recognizable. All typical vertebrae have a common plan of structure, which must first be understood. A vertebra consists of a body, arch and processes.

        
        

        
        

        Body or Centrum:

        
        

        • Mass of bone on which vertebra is built.
        • It is cylindrical, solid and rod like.
        • The dorsal surface of the body forms the floor of neural (spinal) canal.
        • The ventral surface presents ill developed spines called infraspinatus process, for muscular attachment.
        • The centrum is convex anteriorly and concave posteriorly.
        • The vertebra are articulated to each other both at the centrum and oblique process.

        Arch:

        
        

        • The neural arch consists of lamina and the pedicle, together. (Dorsally, from either side of the body spring plates of bones called pedicles which form the wall of the neural ring. They unite above to form the roof and are called laminae).
        • The arches of the opposite sides unite together to complete the neural ring.
        • Series of neural rings with intervertebral membrane constitute the neural canal, which lodges the spinal cord.
        • The pedicles bear notches at their cranial and caudal aspects, which form a circular opening together with preceding vertebra called intervertebral foramen, through which the spinal nerves and vessels pass.

        Processes:

         

        A)    Spinous processes: 

        a) Supraspinous process/Neural Spine/ Dorsal spine:

        ·         It is a single process project dorsally form the middle of the arch, where the two laminae meet.

        ·         It varies greatly in form, size and direction in different vertebrae.

        ·         It furnishes attachment to muscles and ligaments. 

        b) Infraspinous process:

        • Its is on the ventral part of the centrum.
        • Some vertebrae also have a ventral tubercle, ventral crest or a hemal arch. 

        B) Oblique/Articular Processes:

        • The vertebral segments articulate with each other, both at centrum and at oblique process.
        • The oblique processes are four in numbers, two being placed anteriorly and two posteriorly.
        • They bear a small articular part.
        • The anterior oblique process faces above and articulates with the posterior oblique process of the preceding vertebra, which look ventrally.
        • They are called oblique process due to their placement.

        C) Transverse processes:

        • Are two in number and project laterally from the sides of the arch or from the junction of the arch and body.
        • In the cervical region the transverse processes of the 3rd to 6th cervical vertebrae present a cranial and caudal portion.
        • The transverse processes are pierced by the transverse foramen(foramen transversarium) at their base. 

         D) Mamillary processes:

        • Are found in most animals on the caudal thoracic and cranial lumbar vertebrae between the transverse and cranial articular processes or on the latter. 

         E) Accessory processes:

        • When present, are situated between the transverse and caudal articular processes.

        
        

        THE CERVICAL VERTEBRA

        • The vertebral segments of neck (cervical) region are called cervical vertebra and are seven in number.  
        • Placed serially one behind the other, being designated as first (atlas), second (axis), third, fourth, fifth, sixth and seventh cervical vertebra.
        • They have long cylindrical centrum. They decrease in length from before backwards, while their width increases.
        • The oblique processes are well developed and form diarthrodial joints.
        • The first cervical vertebra(atlas) is completely an atypical where as the second cervical vertebra(axis) is partially an atypical or typical. Rest of the vertebrae of this segment are typical.

        ATLAS

        ·     It widely differs from the rest of vertebrae, hence, it is called an atypical vertebra.

        ·     In domestic animals head is suspended form atlas where as in human, atlas carries the head.

        • It presents a ring and two large plates of bone, termed wing or alae.

        Ring:

        ·     Ring is more or less rounded.

        ·     It has 4 surfaces: anterior, posterior, dorsal and ventral.

        ·    The dorsal surface presents a raised eminence called dorsal tubercle, which represents     supraspinous process of other vertebra.

        ·     On the ventral surface there is an obtuse eminence called ventral tubercle.

        •  The anterior surface present two foramen; vertebral foramen (antero-internal) and the     foramen alare (antero-external) connected by a short furrow.

        ·     On the posterior surface there is a smooth articular surface called fovea dentis, which lodges odontoid process of the axis.

        ·    The ring anteriorly presents on either side a deep articular cavity which receive the occipital condyle of skull.

        • The ring posteriorly presents two articular surface (fovea dentis and lateral articular surface) for articulation with the anterior surface odontoid process and articular surface) of axis.

        

        Wing or Alae:

        ·     The wing represents transverse process of the typical vertebra.

        ·      It presents dorsal and ventral surfaces.

        ·      On the dorsal surface of the wing just behind the foramen alare (1st) and vertebral foramen (2nd), there are the external openings of the third and fourth foramina.

        ·      On the ventral surface at the junction of the ring, there is a deep fossa atlantis.

        ·       Foramen transversarium is absent.

        
        

         AXIS

        ·     It is longest of the vertebrae and partly atypical.

        ·     On the anterior part of the body, there is a projection called odontoid process (dens), which is dorsally deeply concave and rough and ventrally articular, smooth and convex.

        ·     On the either side of the odontoid process, there are extensive, nearly flat articular surface, which may be considered as modified anterior oblique process. They blend with the ventral surface of the odontoid process. The entire surface thus, articulates with the fovea dentis of the atlas. 

        ·     The intervertebral foramen is present a little behind the anterior notch, which is circular.

        ·     The infraspinous process is in the form of median ridge and the supraspinous process projects a little infront over the canal.

        ·     Posterior oblique process placed posterolateral over the canal.

        ·    The foramen transversarium is either small or absent.

        
        

        

        THE THIRD, FOURTH AND FIFTH CERVICAL VERTEBRA

        ·         These vertebrae are similar with typical vertebrae.

        ·         In serial placement the bodies tend to become shorter and wider form front to backwards.

        ·         The supraspinous process is short and tuberous centrally in the third, then gradually increases in height and length upto the seventh with forward inclination.

        ·         Ventrally, projects a well defined infraspionus process with increseas in length and angle of descend.

        ·         The oblique processes are slightly convex anteriorly and concave posteriorly, the size of which increases with the receding number.

        ·         The oblique processes are slightly convex anteriorly and concave posteriorly, the size of which increases with the receding number.

        ·         The transervse processes are divided into upper tubercular portion (project at right angles) and lower plate like portion directed outwards, downwards and forwards.

        ·         At the base of tubercular transverse process, the foramen transversarium is present. Series of these foramina continue to form canalis transversarious.

        The centrum is convex anteriorly and concave and deep posteriorly.

        
        

        
        

        

        
        

        THE SIXTH CERVICAL VERTEBRA

        ·     It is a typical vertebra.

        ·    The supraspinous process is well developed, while the infraspinous process is absent.

        ·    The oblique process is larger.

        ·   The transverse process is divided and the lower part is modified to form ventral branch of transverse process and laterally it forms lateral branch of transverse process, and is pierced at the base by the foramen transversarium, which is very large (largest in the series).

        
        

        
        

        

        
        

        THE SEVENTH CERVICAL VERTEBRA

        ·   It is a typical vertebra.
        ·     It bears the characters of both cervical and thoracic segments.
        ·     The supraspinous process is highest in the series.
        ·     Infraspinous process is represented by two tubercles.
        ·     The foramen transversarium is absent.
        ·     The transverse process is undivided.
        ·   The neural ring is very large.

        ·   Two semilunar demi facet are present on either side of posterior concave articular surface, which              together with head of first thoracic segment completes the articular cavities for the head of first pair        of ribs.

        
        

        
        

        
        

        
        

        THE THORACIC OR DORSAL VERTEBRAE

        ·     There are 13 thoracic vertebrae in this region.

        ·     The vertebrae of this region are characterized by the presence of articular surface on the bodies for the heads of the ribs and on the transverse process for the tubercles of the ribs; and by the excessive development of supraspinous process.

        ·    The supraspinous process is well developed and highest.

        ·    The infraspinous process is in the form of thin ridge.

        ·    The oblique process is small. The anterior oblique process is slightly convex and placed on the dorsal part, directed upward. The posterior oblique process are slightly concave and placed at the base of dorsal spine, face downwards.

        ·    The transverse process are short, thick and single.

        ·    Each transverse process bears a tubercular facet on its ventral aspect for articulation with the tubercle of rib. They bear a thick rounded mamillary process on the dorsal aspect, which may be absent or ill developed in last few segments.

        ·    The bodies are short, distinctly constricted in the middle and are expanded at the   extremities.

        ·     On the either side at either end of the articular extremities of the centrum, there is a   concave articular surface, termed as costal facet. Each is a demi-facet as it articulates   with half the part of the head of rib.

        ·     The vertebral notches are shallower and smaller but anterior notches are deeper.

        ·     The arch is perforated by an additional intervertebral foramen on either side, in the posterior segments.

        ·     Spine of the first is pointed backwards. This backwards inclination increase up to the   tenth and then decrease.

        ·   The summits of the seventh to tenth are distinctly bifid.

             

        
        

        

        
        

        The FIRST THORACIC VERTEBRA

        
        

          ·      It shares the characters of both the thoracic and cervical vertebrae.

         ·     The costal and tubular facets are the largest in the series so also the transverse process

         ·     The supraspinous process suddenly rises in height

         ·   The anterior oblique process resemble those of cervical region.   

        
        

        
        

        

        
        

        
        

        
        

        The LAST THORACIC VERTEBRA

        
        

        ·   The body is oval and bears no posterior pair of costal facet.

        ·  The supraspionus process is vertical of slightly incline forward.

        
        

        
        

        
        

        THE LUMBAR VERTEBRAE

        
        

        ·   There are six lumbar vertebra and form the skeleton of loins.

        ·    Excessive development of transverse process is a special character.

        ·    Each transverse process is a long plate of bone, the transverse processes are   separated by intertransverse space. The length of first transverse process is the   shortest. It gradually increases up to 4th & 5th. The 6th is slightly shorter than the 5th.

        ·    The supraspinous process is broad and flattened.

        ·    The oblique process is well developed. The anterior oblique process is strongly   curved, facing inwards, while the posterior ones are correspondingly convex.

        ·    The mammillary process are fused with the anterior oblique processes , which are   thick and tuberous.

        ·     The bodies of lumbar vertebra are constricted in the middle, expanded at the   extremities and resemble as thoracic vertebrae.

        ·     The neural canal is uniform up to 3rd and increase in length and height up to the last.

        ·     The posterior notches are larger than the anterior ones.

              ·  The intervertebral foramen frequently doubles in the anterior few segments.

        
        

        

        
        

        
        

        THE FIRST LUMBAR VERTEBRA

        
        

        ·    Body is small and cylindrical.

        ·    Articulates anteriorly with the last thoracic segment.

        ·  Space between the two anterior processes is the shortest in the series, so also the intertransverse space.

        
        

        
        

        THE SIXTH LUMBAR VERTEBRA

        
        

        ·    Body is compressed form above downwards.

        ·    Neural ring is very wide.

        ·    Oblique processes are placed wide apart.

        ·  Supraspinous process is smallest in series.

        
        

        THE SACRUM

        The sacrum consists of five sacral bones fused together to form a single bone. It forms the region of croup.

        Direction: it is horizontal in direction.

        Location: Located between lumbar vertebrae anteriorly and coccygeal vertebrae posteriorly.

        Relation : it articulates with the ilium, anteriorly with last lumber and posteriorly with the first coccygeal vertebra.

        Shape: it is aeroplane shape. 

        
        

        

        
        
        

        

        
        

        Composition: it present 2 surfaces, 2 borders, a base and an apex.

        Surface:

        Dorsal surface:

        ·        Presents centrally five sacral spines, which are fused together to form the medial sacral crest.

        ·        On other side of the base of the median sacral crest are the lateral sacral crest, which are the fusion of the oblique processes.

        ·        There are 4 pairs of dorsal sacral foramina, of which the 1st & 2nd pairs are located internal to lateral sacral crest, and the remaining are external to the lateral sacral crest.

        ·        Neural rings are triangular, anterior larger and posterior smaller.

         

        Ventral Surface:

        ·        It forms the roof of the pelvic cavity and is concave from side to side and from before backwards.

        ·        It presents 4 pairs of ventral sacral foramina, and 4 transverse lines and one central median longitudinal furrow (sulcus vasculosus).

        Borders:

        The two lateral borders are thin, sharp, concave and irregular.

        Base:

        ·        It is the anterior extremity of the first sacral vertebra.

        ·        It consists of body and two alae or wings.

        ·        The body is located centrally and is concave.

        ·        The wings are anteriorly concave and articulate with ilium by auricular facet.

        Apex:

        ·        Apex is the posterior end of 5th sacral vertebra and is slightly wider than the 4th sacral vertebra.

        ·        It has centrally a small triangular neural ring.

        ·        On either side of the centrum of the last segment are backward projections, which represent the transverse process of the last sacral vertebra.

        Comparison with:

        A) Sacrum of Horse: (S5)

        ·        Supraspinous process is distinct.

        ·        Four dorsal sacral foramina are on either side of the base of spines.

        ·        The lateral sacral crest is suppressed.

        ·        Lines transversae are less distinct.

        ·        The ventral sacral foramina are smaller than that of ox.

        ·        The auricular surface is elongated, oval and large.

        B) Sacrum of Dog: (S3)

        ·        Median sacral crests are in the form of two tubercles.

        ·        Lateral sacral crests are two in number.

        ·        The wings are high and auricular surfaces are directed outwards.

        ·        The ventral foramina are two in number.

        C) Sacrum of Pig: (S4)

        ·        Supraspinous process is ill developed.

        ·        Body is less curved.

        ·        Cranial articular processes are well developed.

        D)  Sacrum of Fowl: (L+S14)

        ·        Lumbar and sacral vertebrae are fused to form a single synsacrum.

        ·    This bone remains articulated with the ilia along their lateral borders.

        
        

        
        

        THE COCCYGEAL VERTEBRA

        ·        The coccygeal or tail region consists of 15-20 segments.

        ·        In the first three of four, all the characteristics features of a true vertebra are found.

        ·        The first coccygeal vertebra may be fused with sacrum.

        ·        The first five have complete neural arches, supraspinous processes and large transverse processes. Anterior oblique processes are very distinct, but don't form ant articulation.

        ·        The first 12 present two small processes on the ventral surface of the bodies, the haemal processes, which pass the middle coccygeal artery.

        ·        Oblique processes disappear from the 7th or 8th.

        
        

        

        
        
        

        Comparison of different vertebrae with:

        A) Horse:

                    C7 T18 L6 S5 Cy15-21

        ·        Body of cervical vertebra is longer.

        ·        Wing of the atlas are pierced posteriorly by foramen transversarium.

        ·        Mamillary processes are in few caudal segments of thoracic vertebrae which are more developed.

        ·        Coccygeal vertebrae are shorter and ill developed.

         

        B) Dog:

                    C7 T13 L7 S3 Cy20-23

        ·        Foramen transversarium is present in the atlas at its posterior aspect.

        ·        In lumbar vertebrae, the spinous processes are comparatively short, broad ventrally and narrow dorsally.

        ·        Coccygeal vertebrae are better developed.

         

        C) Pig:

                    C7 T14-15 L6-7 S4 Cy20-23

        ·        Cervical vertebrae are short and bodies are wide.

        ·        Thoracic vertebrae are comparatively long.

        ·        Spinous processes of cervical vertebrae are short but large in axis.

        ·        First few coccygeal vertebrae present well-developed articular processes. 

        
        

        D)  Fowl:

                    C14 T7 L+S14 Cy6

        ·        In general, the vertebral column is rigid & stiff due to fusion of some vertebral   segments.

        ·        Atlas is in the form of ring, presents only one articular facet for single occipital condyle.

        ·        Cervical vertebrae have styloid projections from transverse processes.

        ·     Last few caudal vertebrae fuse to form a pointed bony projection, known as pygostyle.

        
        

        
        

        THE RIBS

           It presents a shaft and 2 extremities.

        Shaft:

        It is elongated and curved more at the upper part, while it is twisted and turned inwards at the lower part.

        It presents 2 surfaces and 2 borders.

        Surfaces:

        ·        The lateral surface is convex and is market by a wide groove on its anterior part.

        ·        The medial surface is concave, smooth and is covered by pleura.

         

        Borders :

        ·   Anterior border is thick and concave.

        • Posterior border is convex and presents costal groove.

         

        Extremities:

        Proximal extremity:

        ·        Consists of head, neck and tubercle.

        ·        Head (capitulum) is rounded and has a hemispherical articular surface, which is divided into two convex facets, anterior & posterior by a groove (sulcus capituli). It articulates with the costal facet placed on the body of thoracic vertebra.

        ·        Neck (collum costae) is a long constriction below the head and separates the head from tubercle.

        ·        The tubercle (tuberculum costae) bears a concave facet for articulation with tubercular facet of the thoracic vertebrae.

         

        Distal/Sternal Extremity

        • It is either articular or is prolonged by a costal cartilage.

        

        
        

        Characters of Ribs in Serial placement:

        ·        The first rib is shortest, thickest and last curved. It body widens greatly towards the distal end. The costal groove is absent.

        ·        The 8th, 9th & 10th ribs are generally the longest and the widest.

        ·        The head and tubercle decrease in size from the first to last ribs.

        ·        The curvature of the ribs increases from the first to last.

        ·        The last rib is slender and curved. The head and the tubercle of this rib are smallest and fuse with each other and hence neck is absent.

        ·        The distal extremity is thin and prolonged by the costal cartilage.

         

        THE COSTAL CARTILAGES

        ·        It is the prolongation of rib, which helps to complete the lateral walls of the thorax.

        ·        Each is a cylindrical piece of cartilage, slightly compressed from sides to sides.

        ·        It is rounded and smooth on its borders and surfaces.

        Comparison with:

        A) Ribs of Horse:

        ·        18 pairs of ribs, eight sternal and ten asternal.

        ·        11th is longest and 6th is the widest rib.

        ·        Costal groove is distinct on the 4th to 8th ribs and absent on the first.

        B) Ribs of Dog:

        ·        13 pairs of ribs, nine sternal and four asternal.

        ·        The first eight or nine increase in width at their distal extremity.

        ·        The last three of four ribs articulate with anterior costal facets, the posterior being rudimentary.

        ·        First rib is very long and highly curved.

        C) Ribs of Pig:

        ·        14-15 pairs of ribs, 7 sternal and 7-8 asternal.

        ·        The first rib has prismatic body.

        ·        The last rib is usually small and floating

        D)  Ribs of Fowl:

        ·        7 pairs of ribs.

        ·        Each rib has a dorsal 7 ventral segment.

        ·        First two ribs don’t extend up to sternum.

        • Each of the dorsal segments of 2nd-6th ribs processes a caudal extension, called uncinate process, which supports the thoracic cage in a better way of overlapping the succiding rib.

        
        

        THE STERNUM(Breast bone)

        ·        It is centrally placed, segmented, osteo-cartilagenous structure, forming the floor of the thoracic cavity.

        ·        It is held in suspension by the costal cartilage.

        ·        In the adult animals, it consists of seven segments (sternebrae), which are elongated from before backwards.

        ·        Sternum is compressed laterally in the front, and dorso-ventrally behind.

        ·        It is oblique direction pointing downwards and backwards.

        
        

        

        
        

        

        
        

        It presents 2 surfaces, 2 borders and 2 extremities.

        Surface:

        Dorsal surface

        ·        It is flat and rough, widens from before backwards and becomes much constricted behind the last pair of costal facets.

        Ventral surfaces :

        ·        It is strongly convex anteriorly and is flat and depressed behind. It is market by a faint median longitudinal ridge, which divides the surface into two equal halves.

        ·        Ventral crest is absent.

        Borders:

        2 lateral borders

        Lateral borders:

        ·        Divide the dorsal and ventral surface. Each border separates anteriorly into dorsal and ventral divisions to enclose 7 sternal facets.

        Extremities

        Anterior extremity

        ·        It is cranial end of the 1st strnebra and forms the presternum or manubrium sterni.

        ·        It is compressed laterally and is placed at an angle in front of the 2nd sternebra.

        ·        It bears a facet for articulation with the first costal cartilage on either side.

         

        Posterior extremity:

        ·        It is prolonged by the xiphoid cartilage. It is concave above and convex below.

        Comparison with

        Sternum of horse:

        ·        Fusion of seven sternebrae.

        ·        Boat shaped, compressed laterally towards the cranial end and dorso-ventrally at the caudal end.

        ·        Lateral surfaces are convex.

        ·        Ventrally it presents a prominent crest.

        ·        Xiphoid cartilage is flat and rounded.

         

        Sternum of dog:

        ·        Formed by 8 sternal segments, which generally don’t fuse with each other. Many fuse at very old age.

        ·        First sternebra is longest.

        ·        Cranial end is blunt and the xiphoid cartilage is narrow.

         

        Sternum of Pig:

        ·        Six sternebrae has fused to form this bone

        ·        Bone is dorso-ventrally compressed.

        ·        Xiphoid process is long and xiphoid cartilage is small.

         

        Sternum of Fowl:

        ·        It is large irregular plate of bone composed of cranial mass.

        ·        Cranial mass has:

        o   Cranial projection : rostrum

        o   Caudal extension: metasterum and lateral process.

        o   Dorsal surface is concave.

        o   Ventrally presents a plate like bone, which is extended up to the metasternum known as sternal crest or keel or crania.

        ·        The rostrum presents tow facets for coracoids.

        ·        The lateral processes are