222 



THE ARTICULATIONS OF THE HORSE 



C.u. 



lar surface of the radius above and the metacarpus below; its deep face is also 

 attached to a considerable extent to the carpal bones and to the small ligaments. 

 Its anterior part, the dorsal carpal ligament, is loose, except during flexion, and 

 assists in forming the fibrous canals for the extensor tendons. Its posterior part, 

 the volar carpal ligament (Lig. carpi volare), is very thick and dense, and is closely 

 attached to the carpal bones. It levels up the irregularities of the skeleton here, 

 and forms the smooth anterior wall of the carpal canal. It is continued downward 

 to form the subcarpal or inferior check ligament, which blends with the tendon of 

 the deep flexor of the digit about the middle of the metacarpus, and may well be 

 regarded as the carpal (tendinous) head of that muscle. 



The synovial membrane forms three sacs corresponding to the three joints. 



The radio-carpal sac is the 

 most voluminous; it includes 

 the joints formed by the acces- 

 sory carpal bone, and also those 

 between the proximal carpal 

 bones as far as the interosseous 

 ligaments. The intercarpal sac 

 sends extensions upward and 

 downward between the bones 

 of the two rows as far as the 

 interosseous ligaments ; it com- 

 municates between the third 

 and fourth carpal bones with 

 the carpo-metacarpal sac. The 

 latter is very limited in extent, 

 and is closely applied to the 

 bones; it incloses the carpo- 

 metacarpal joint, and lubri- 

 cates also the lower parts of 

 the joints between the distal 

 carpal bones and the inter- 

 metacarpal joints. 



The lateral ligament (Lig. 

 carpi collaterale ulnare) is at- 

 tached above to the lateral 

 tuberosity of the distal end of 

 the radius. Its long superficial 

 part is attached below to the 

 proximal end of the lateral 

 small metacarpal chiefly, but 

 some fibers end on the large 

 metacarpal bone. A canal for the lateral extensor tendon separates a short deep 

 band which ends on the ulnar carpal bone. Other deep fibers connect the latter 

 with the fourth carpal bone, and the fourth carpal with the metacarpus. 



The medial ligament (Lig. carpi collaterale radiale) resembles the preceding 

 in general, but is stronger and wider distally. It is attached above to the medial 

 tuberosity of the distal end of the radius and ends below on the proximal ends of 

 the large and medial smaU metacarpal bones. Deep fasciculi are detached to the 

 radial and second carpal bones. The first carpal bone, when present, is usually 

 embedded in the posterior part of the distal end of the ligament. The posterior 

 part of the ligament is fused with the transverse ligament of the carpus (Lig. carpi 

 transvcrsum), and concurs in the formation of a canal for the tendon of the flexor 

 carpi radialis. 



Mc. IV 



Mc. Ill 



The 



Fig. 23S. — Left Cahpal Joints of Horse; Dohsal A'iew, 

 Joint Capsule is Removed. 

 H, Lateral distal tuberosity of radius; M, medial ligament; L, 

 lateral ligament; C. r., radial carpal bone; C. u., ulnar carpal bone; 

 C. S, third carpal bone; C. 4, fourth;Carpal bone; Mr. Ill, Mc. I\\ 

 metacarpal bones; 1, intermediate carpal bone; 2-6, dorsal ligaments. 



