VETERINARY COMPARATIVE ANATOMY
Doctor of Veterinary Medicine 1
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Module No. 2: Locomotor System / Musculoskeletal System - Horse: it extends over the caudal angle and reaches the level of the
withers
The Skeletal System - Carnis: only a small band
I. Axial ● Lateral surface
II. Appendicular ○ Spine of the scapula/ scapular spine
III. Splanchnic/ visceral skeleton – bones formed in the viscera or soft organs ■ Ends w/ a well-defined prominence acromion
● Os cordis (heart of cattle & sheep) ● In carni & rums: close to ventral angle
● Os penis (penis of dogs, beaver, racoons, walruses) ● In horse & pig: subsides distally
● Os rostri (in nose of pigs) ● prominence is extended to form a distinct process in the
dog & cat (suprahamate process)
II. Appendicular ■ Tuber of the spine is present except in carnis
- is made up of the bones of the main appendages of the animal body → limbs ○ Smaller cranial supraspinous fossa
● Thoracic limb ○ Larger caudal infraspinous fossa
● Pelvic limb ● Medial or costal surface hallowed by a shallow fossa
● costal surface of the scapula: hollowed by the shallow subscapular fossa
Skeleton of the thoracic limb ● Outline of the scapula can be defined by different features:
- Bones of the thoracic limb: ○ cranial angle – joins the thin and slightly concave cranial border
● Scapula ○ cranial border – forms scapular notch at the level of the neck of the
● Humerus scapula
● Radius ○ ventral angle – carries the shallow glenoid cavity
● Ulna ○ caudal border
● Carpal bones ○ caudal angle
● Metacarpal bones ○ dorsal border
● Digital bones / phalanges ● Glenoid cavity – for the articulation of the scapula with the humerus
- Joints of thoracic limb ● Supraglenoid tubercle
● Shoulder joint ● Coracoid process
● Elbow joint
● Radioulnar joint
● Carpal joint (5)
● Metacarpophalangeal joint/fetlock joint
● Proximal interphalangeal joints/pastern joint
● Distal joint
Pectoral girdle – joins the forelimb to the trunk
- Comprises the:
● Coracoid
● collar bone
● shoulder blade / scapula
Skeleton of the thoracic limb: Scapula
- is triangular in outline and lies flat against the cranial part of the lateral thoracic
wall
- most proximal bone of the thoracic limb
● Dorsal border
● Scapular cartilage: crescent shaped; acts as a shock absorber
Comparative Anatomy of the Scapula
, 2
- Shape ● Humerus – a single bone that formed the skeleton of the proximal part of the free
- Scapular cartilage appendage of the forelimb
- Scapular spine - central function in the movement of the thoracic limb
- Acromion ● Humerus can be divided into three basic segments:
- Trapezius tubercle ○ proximal extremity bearing the head and the tubercles
○ shaft of humerus bearing the deltoid tuberosity
Species Scapula characteristics
○ distal extremity bearing the humeral condyle
● Proximal extremity:
Dog vertebral border convex
○ carries the head of the humerus which articulates w/ glenoid cav of
Caudal angle thick
scapula
Spine central – divides the fossa in two equal parts
○ Neck – most pronounced in the dog and cat
No trapezius tubercle
○ greater tubercle – craniolateral side of the humeral head
Acromion process well-developed
- has cranial & caudal part except in cat
○ lesser tubercle – craniomedial side
Horse Shape: triangular - is divided into two parts in rums & horse
Vertebral border irregular and large scapula cartilage ○ bicipital groove – sub divided by a flat protuberance in rums;
Supraspinous fossa slightly smaller than infraspinous fossa prominent ridge in the horse
Trapezius tubercle prominent ● humeral shaft or body – middle part of the humerus
Acromion process absent
● deltoid tuberosity – located on the lateral aspect of the humeral shaft; extends
distally as the humeral crest
Ox Shape: triangular ● In rums & horse: teres major tuberosity is located on the medial surface of the
Vertebral border more regular than that of horse cartilage often absent n humeral shaft
prepared specimen. ● In carnis: tuberosity is replaced by the crest of the lesser tubercle
Supraspinous fossa much smaller than infraspinous fossa ● Distal extremity:
No trapezius tubercle ○ bears humeral condyle → articulates with the bones of forearm:
Acromion process well-defined radius & ulna to form elbow joint
Coracoid process ill-defined
○ Epicondyles; lateral epicondyle – attachment of extensor mm;
medial epicondyle – for the flexor mm
Pig Shape: triangular ● Epicondyles separated by olecranon fossa; radial fossa is situated on the
Vertebral border convex cranial aspect of the condyle – only found in dogs
Spine almost central ○ In dog: olecranon fossa and the radial fossa communicate through a
Very large trapezius tubercle which overlaps infraspinous fossa with a large supratrochlear foramen – no structure passes thru unlike in cats
deltoid tuberosity ○ In cat: medial aspect of the distal extremity of the humerus is perforated
Absence of acromion by the supracondylar foramen
● Elbow joint – formed by the articulation of humeral condyle and olecranon
Bird scapula: complete pectoral girdle process of the ulna
● Scapula - immobile
● Coracoid - from sternum to shoulder joint Birds humerus:
● Clavicle - wishbones (left & right) - Thin
- Pneumatized (long bones)
Synsarcosis - Medullary cavity
● Arrangement of mm, tendons & fascia - Pectoral crest
● Forelimb to axial skeleton
Skeleton of the arm (brachium)
Doctor of Veterinary Medicine 1
_____________________________________________________________________________________________________________________________________
Module No. 2: Locomotor System / Musculoskeletal System - Horse: it extends over the caudal angle and reaches the level of the
withers
The Skeletal System - Carnis: only a small band
I. Axial ● Lateral surface
II. Appendicular ○ Spine of the scapula/ scapular spine
III. Splanchnic/ visceral skeleton – bones formed in the viscera or soft organs ■ Ends w/ a well-defined prominence acromion
● Os cordis (heart of cattle & sheep) ● In carni & rums: close to ventral angle
● Os penis (penis of dogs, beaver, racoons, walruses) ● In horse & pig: subsides distally
● Os rostri (in nose of pigs) ● prominence is extended to form a distinct process in the
dog & cat (suprahamate process)
II. Appendicular ■ Tuber of the spine is present except in carnis
- is made up of the bones of the main appendages of the animal body → limbs ○ Smaller cranial supraspinous fossa
● Thoracic limb ○ Larger caudal infraspinous fossa
● Pelvic limb ● Medial or costal surface hallowed by a shallow fossa
● costal surface of the scapula: hollowed by the shallow subscapular fossa
Skeleton of the thoracic limb ● Outline of the scapula can be defined by different features:
- Bones of the thoracic limb: ○ cranial angle – joins the thin and slightly concave cranial border
● Scapula ○ cranial border – forms scapular notch at the level of the neck of the
● Humerus scapula
● Radius ○ ventral angle – carries the shallow glenoid cavity
● Ulna ○ caudal border
● Carpal bones ○ caudal angle
● Metacarpal bones ○ dorsal border
● Digital bones / phalanges ● Glenoid cavity – for the articulation of the scapula with the humerus
- Joints of thoracic limb ● Supraglenoid tubercle
● Shoulder joint ● Coracoid process
● Elbow joint
● Radioulnar joint
● Carpal joint (5)
● Metacarpophalangeal joint/fetlock joint
● Proximal interphalangeal joints/pastern joint
● Distal joint
Pectoral girdle – joins the forelimb to the trunk
- Comprises the:
● Coracoid
● collar bone
● shoulder blade / scapula
Skeleton of the thoracic limb: Scapula
- is triangular in outline and lies flat against the cranial part of the lateral thoracic
wall
- most proximal bone of the thoracic limb
● Dorsal border
● Scapular cartilage: crescent shaped; acts as a shock absorber
Comparative Anatomy of the Scapula
, 2
- Shape ● Humerus – a single bone that formed the skeleton of the proximal part of the free
- Scapular cartilage appendage of the forelimb
- Scapular spine - central function in the movement of the thoracic limb
- Acromion ● Humerus can be divided into three basic segments:
- Trapezius tubercle ○ proximal extremity bearing the head and the tubercles
○ shaft of humerus bearing the deltoid tuberosity
Species Scapula characteristics
○ distal extremity bearing the humeral condyle
● Proximal extremity:
Dog vertebral border convex
○ carries the head of the humerus which articulates w/ glenoid cav of
Caudal angle thick
scapula
Spine central – divides the fossa in two equal parts
○ Neck – most pronounced in the dog and cat
No trapezius tubercle
○ greater tubercle – craniolateral side of the humeral head
Acromion process well-developed
- has cranial & caudal part except in cat
○ lesser tubercle – craniomedial side
Horse Shape: triangular - is divided into two parts in rums & horse
Vertebral border irregular and large scapula cartilage ○ bicipital groove – sub divided by a flat protuberance in rums;
Supraspinous fossa slightly smaller than infraspinous fossa prominent ridge in the horse
Trapezius tubercle prominent ● humeral shaft or body – middle part of the humerus
Acromion process absent
● deltoid tuberosity – located on the lateral aspect of the humeral shaft; extends
distally as the humeral crest
Ox Shape: triangular ● In rums & horse: teres major tuberosity is located on the medial surface of the
Vertebral border more regular than that of horse cartilage often absent n humeral shaft
prepared specimen. ● In carnis: tuberosity is replaced by the crest of the lesser tubercle
Supraspinous fossa much smaller than infraspinous fossa ● Distal extremity:
No trapezius tubercle ○ bears humeral condyle → articulates with the bones of forearm:
Acromion process well-defined radius & ulna to form elbow joint
Coracoid process ill-defined
○ Epicondyles; lateral epicondyle – attachment of extensor mm;
medial epicondyle – for the flexor mm
Pig Shape: triangular ● Epicondyles separated by olecranon fossa; radial fossa is situated on the
Vertebral border convex cranial aspect of the condyle – only found in dogs
Spine almost central ○ In dog: olecranon fossa and the radial fossa communicate through a
Very large trapezius tubercle which overlaps infraspinous fossa with a large supratrochlear foramen – no structure passes thru unlike in cats
deltoid tuberosity ○ In cat: medial aspect of the distal extremity of the humerus is perforated
Absence of acromion by the supracondylar foramen
● Elbow joint – formed by the articulation of humeral condyle and olecranon
Bird scapula: complete pectoral girdle process of the ulna
● Scapula - immobile
● Coracoid - from sternum to shoulder joint Birds humerus:
● Clavicle - wishbones (left & right) - Thin
- Pneumatized (long bones)
Synsarcosis - Medullary cavity
● Arrangement of mm, tendons & fascia - Pectoral crest
● Forelimb to axial skeleton
Skeleton of the arm (brachium)
