84 



THE SKELETON OF THE HORSE 



the radius The inferior or distal surface is smaller, convex m front, concave be- 

 hind and articulates with the third and fourth carpal bones The internal surface 

 has upper and lower facets for articulation with the radial carpal, and between 

 these it is excavated and rough. The external surface is similar to the preceding 

 and articulates with the ulnar carpal. The anterior or dorsal surface is rough and 

 slightly convex. The posterior or volar surface bears a tuberosity on its lower part. 



The Ulnar Carpal Bone 

 The ulnar carpal bone (Os carpi ulnare, cuneiform) is the smallest and most 

 irregular bone of the upper row. The superior or proximal surface is concave a^^^^^ 

 fits the lower part of the outer facet on the distal end of the radius. The mfenor 

 or distal surface is oblique and undulating for articulation with the fourth carpal 

 bone The internal surface has upper and lower facets for articulation with the 

 intermediate The anterior or dorsal and external surfaces are continuous, convex 

 and rough. The posterior or volar surface is oblique, and bears a concave iacet 

 for articulation with the accessory carpal bone; below this is a tubercle. 



T-v „ TTr. t^-i Left Carpal Bones of Horse, with 



F,,. 52.-LKFT Carpal Bones of Horse, with Dis- Fig. 53^ Left Car ^^^ Metacarpus; 



TAL EKn OF Radius anb Proximal En. of ^^^I View. 



Metacarpus; Internal View. i. rr / fir«t tn 



Atlas d. Anat. il. Pferdes.) 



The Accessory Carpal Bone 

 The accessory carpal bone (Os carpi acccssorium, pisiform) is situated lieliiml 

 the u nar earpai ,«ue Id the outer part of the distal end of the u na. « >-!-- 

 and presents for description two surfaces and a circuniference The in ema 

 surface is concave and forms the outer wah of the carpal groove The external 

 surface s convex and rough; a smooth groove for the out^cr tendon of the flexor 

 cC exteruus crosses its anterior part obliquely downward and slightly forward. 

 Thi anterior border bears two facets; the upper one is concave and articulates with 

 the back of the outer facet on the distal end of the radius; the lower one is convex 

 and articulates with the ulnar carpal bone. The remainder of the circumference is 

 rounded and rough. 



^J'^:^^\^S:^t^^^J^ c'SSr-S.'autthe fle.o. of the digit. 



