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| − | ==Common structures of the Proximal Forelimb and Shoulder== | + | ==Structures of the Proximal Forelimb and Shoulder== |
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| | ===Scapula=== | | ===Scapula=== |
| − | | + | *The ox possesses a small '''tuber scapular''' |
| − | The Scapula forms the basis of the shoulder region, providing points of attachment of extrinsic and intrinsic muscles. It is held in place by a synsarcosis of muscles and does not form a conventional articulation with the trunk.
| + | *It has '''acromion''' present |
| − | *In ungulates, the dorsal border is extended by a scapular cartilage, which enlarges the area for muscle attachment. This ossifies with age.
| + | *It has extensive scapular cartilage |
| − | *The bone is roughly triangular, with a prominent '''spine''' that can be palpated through the skin | |
| − | *The spine defines '''Infraspinous''' and '''Supraspinous''' '''Fossae''', inhabited by muscles accordingly | |
| − | *The spine serves as a point of attachment for the '''trapezius''' muscle
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| − | *The spine culminates in the '''acromion''' in all but the horse and pig
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| − | *Medial muscle attachment comprises mostly of the '''subscapularis''', with the '''serratus ventralis''' attaching dorsally | |
| − | *The Scapula articulates with the humerus at the '''Glenoid cavity'''
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| − | ===Clavicle===
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| − | The Clavicle is all but absent in most domestic species, with the notable exception of the avian skeleton. In the dog and cat, a remnant of bone may remain embedded in the fibrous intersection in the brachiocephalicus, which may prove misleading in radiographic images.
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| | ===Humerus=== | | ===Humerus=== |
| | + | *The humerus is essentially the same conformation as that of the dog. |
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| − | The Humerus is the long bone of the forearm, articulating with the scapula to form the shoulder and the radius and ulna to form the elbow. In situ, it lies obliquely along the ventral thorax and is more horizontal in larger species.
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| − | *The head of the humerus comprises '''greater''' and '''lesser tubercles''', separated by an '''intertubercular groove''' through which runs the tendon of the '''biceps brachii'''
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| − | *The shaft of the humerus takes on a characteristically twisted shape via a groove carrying the '''brachialis''' and '''radial nerve'''
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| − | *Laterally, the '''deltoid tuberosity''' is palpable through the skin and connects to the head of the humerus via a ridge and merges distally with the '''crest of the humerus'''
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| − | *Distally, the humerus culminates in a '''condyle''' which articulates to form the elbow
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| − | **In large animals, it meets the radius via a '''trochlea'''
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| − | **In dogs and cats, it articulates with the radius medially via a trochlea and the ulna laterally via a '''capitulum'''
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| − | **Caudally, all species show an '''olecranon fossa''' which articulates with the '''olecranon''' of the ulna
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| − | *Medial and lateral epicondyles provide attachment for flexors and extensors of the carpus and digits
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| − | ===Radius===
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| − | While in the human the radius and ulna are separated by an interosseus space and articulate only at their extremities, allowing for significant capability of supination and pronation, these movements are much more limited in domestic animals due to the gradual fusing of the two bones. The extreme case is exhibited by the horse.
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| − | *The Radius forms the shaft-like rod of the distal limb, which is bowed to varying degrees amont species
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| − | *The radius articulates proximally with the distal humerus, caudally with the ulna, and distally with the carpus
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| − | *Medially on the distal articular process, a '''styloid process''' projects, which is mirrored laterally by the ulna
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| − | ===Ulna===
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| − | The Ulna's greatest contribution to functional anatomy is in the formation of the '''Olecranon''', or the point of the elbow, which gives rise to the attachment of the '''triceps'''. The olecranon articulates with the humerus via its anconeal process. Distally (where unfused), the '''lateral styloid process''' articulates with the '''ulnar carpal bone'''.
| + | ===Radius and Ulna=== |
| | + | *These are complete bones in the ox but are entirely fused |
| | + | *There is a proximal and distal interosseous space which are the only two places where the shafts are seperated |
| | + | *The ulna's proximal end is caudal to the radius and it's distal end forms the lateral styloid process, distal to the radius and articulating with the ulnar carpal bone. |
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| | ==Joints of the Proximal Forelimb== | | ==Joints of the Proximal Forelimb== |