222 THE ARTICULATIONS OF THE HORSE 
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 
ta most voluminous; it includes 
Ae: Hes the joints formed by the acces- 
sory carpal bone, and also those 
between the proximal carpal 
_R 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 
aT interosseous ligaments; it com- 
municates between the third 
C.u. and fourth carpal bones with 
the carpo-metacarpal sac. The 
latter is very limited in extent, 
c.4 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- 
——Mc.IV_ metacarpal joints. 
The lateral ligament (Lig. 
earpi collaterale ulnare) is at- 
tached above to the lateral 
tuberosity of the distal end of 
R, Lateral distal tuberosity of radius; M, medial ligament; L, the radius. «Its long superficial 
lateral ligament; C.r., radial carpal bone; C. wu., ulnar carpal bone; part is attached below to the 
C. 8, third carpal bone; Cc. 4, fourth. carpal bone; Me. II, Mc. IV, proximal end of the lateral 
metacarpal bones; 1, intermediate carpal bone; 2-6, dorsal ligaments. ; 
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 small 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 
transversum), and concurs in the formation of a canal for the tendon of the flexor 
carpi radialis. 
= Mie ET 
Fic. 238.—Lerr Carpat Jornts oF Horse; Dorsau View. THE 
Jornt CapsuLe 1s REMOVED. 
