QUESTIONS AND ANSWERS 47 



Name the bones of the fore limbs of the horse and state how they 

 differ from those of the ox. 

 In the horse : Scapula, humerus, radius, ulna, scaphoid, lunar, 

 cuneiform, pisiform, trapezoid, magnum, unciform, principal meta- 

 carpus, two rudimentary metacarpi, suffraginis, coronse, pedis, two 

 sesamoids and one naviculare. 



In the ox: Scapula, humerus, radius, ulna, six carpal bones (the 

 OS magnum and trapezoid are fused together), two metacarpi (one 

 principal and one rudimentary, situated outwardly), four digits — 

 two with three phalanges and three sesamoids (as in the single digit 

 of the horse), and two rudimentary ones, composed of two small 

 bones. 



Describe the scapula and name the bone with which it articulates. 



The scapula is a flat, triangular-shaped bone which is applied 

 against the anterior and outer plane of the thorax in an oblique 

 direction downward and forward. 



It has two faces, external and internal; three angles, anterior 

 or cervical, posterior or dorsal, and inferior or humeral, and three 

 borders, anterior, posterior, and superior. 



The external surface is divided by a marked crest, the acromian 

 spine, which runs parallel to the long axis of the bone, into two 

 unequal depressed surfaces, the supra- and infraspinous fossae. 

 The internal face is concave, forming the subscapular fossa, and is 

 roughened for muscular insertion. 



The anterior or cervical angle is comparatively thin, the posterior 

 or dorsal is thick. The inferior or humeral is separated from the 

 rest of the bone by a slight constriction, the neck of the scapula. 

 It presents a glenoid cavity, a round, shallow depression, which 

 receives the head of the humerus, and in front, a coracoid process, 

 with a base and a summit which curves inwardly. 



The superior border is sharp and thin, while the posterior is 

 thick and slightly concave, and the superior is irregular and is 

 prolonged by a thin cartilage, the cartilage of prolongation. 



The scapula articulates with the humerus. 



Describe the ulna. 



The ulna is an elongated, triangular-shaped bone which is applied 

 against the posterior and upper three-fourths of the radius and 

 strongly united with the same. It presents for study a middle por- 

 tion and two extremities. 



The middle portion shows an external smooth, an internal con- 

 cave, and an anterior rough surface which unites with the radius. 

 In the middle third of the anterior surface is seen the ulnar groove 



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