INTERMETACARPAL JOINTS 



223 



_ The accessory carpal bone is connected with adjacent bones by three ligaments (Fig 234) 

 The proximal one is a short band which extends from the accessory carpal in front of the n-oove on 

 Its lateral face and is inserted into the distal end of the radius behind the groove for tfehTuTd 

 extensor tendon A middle^band connects the accessory with the ulnar carpal. The distal ga 



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metacai-pal bone; these bands transmit the 

 action of the muscles which are inserted into 

 the accessory carpal bone. The other bones 

 of the proximal row are connected by two 

 dorsal Ugaments, which are transverse in direc- 

 tion, and two interosseous ligaments. An 

 oblique hgament passes from an eminence on 

 the volar surface of the radial carpal bone to 

 a small depression on the radius medial to the 

 facet for the accessory carpal bone. 



Two ligaments connect the proximal and 

 distal rows posteriorly. The medial one joins 

 the radial to the second and third carpal, and 

 the lateral one attaches the ulnar to the third 

 and fourth carpals. 



The bones of the distal row are con- 

 nected by two strong transverse dorsal 

 ligaments and two interosseous ligaments. 



There are four carpo-metacarpal liga- 

 ments. Two oblique dorsal Ugaments (Ligg. 

 oarpometacarpea dorsalia) connect the third 

 carpal with the large metacarpal bone. Two 

 interosseous ligaments pass downward from 

 the interosseous ligaments of the distal row 

 to end in depressions of the opposed surfaces 

 of the proximal ends of the metacarpal bones. 

 Volar ligaments (Ligg. carpometacarpea vo- 

 laria) connect the second and third carpal 

 bones with the metacarpus. Other short 

 special Ugaments have been described, but 

 some of them at least are artefacts. 



Movements. — Taking the joint as 

 a whole, the chief movements are flex- 

 ion and extension. In the standing 

 position the joint is extended. When 

 the joint is flexed, slight transverse 

 movement and rotation can be pro- 

 duced by manipulation. The dorsal 

 part of the capsule is, of course, tense 

 during flexion, the volar part in exten- 

 sion. 



Fig. 239. — Left Carpal Joints of Horse; Volar View. 

 Accessory Carpal and Capsule have been Re- 

 moved. 



R, Distal end of radius; M, medial ligament; L, 

 lateral ligament; 1, 2, ligaments connecting radial carpal 

 bone and radius; 3, ligament connecting intermediate 

 carpal with radius; 4, stump of ligament connecting inter- 

 mediate and accessory" carpal; 5, ligament connecting radial 

 and second carpal; 6, 6', ligaments connecting second 

 carpal and metacarpal bones; 7, 7', ligaments connecting 

 third carpal and metacarpal bone; 8, ligament connecting 

 ulnar and third and fourth carpal bones ; 9, deep short part 

 of medial collateral hgament; 10, 11, 12, radial, inter- 

 mediate, and ulnar carpal bones; 13, 14, 1.5, second, third, 

 and fourth carpal bones; 16, 16', 17, metacarpal bones. 

 (Of the preceding volar ligaments, 1, 3, and S are distinct 

 from the capsule.) 



The movement practicaUy all occurs at 

 the radio-carpal and intercarpal joints, the 

 articular surfaces of which are widely separ- 

 ated in front during flexion, but remain in 

 contact behind. The distal row remains in 

 contact with the metacarpus. The inter- 

 mediate and ulnar carpals move together as 



one piece, but the radial does not move so far as the intermediate, so that the dorsal and inter- 

 osseous Ugaments connecting these bones become tense and obUque in dhection. 



INTERMETACARPAL JOINTS 



The small joints formed between the proximal ends of the metacarpal bones 

 (Articulationes intermetacarpese) are enclosed by the carpal joint capsule, as des- 

 cribed above. The opposed surfaces of the shafts of the bones are closely united by 

 an interosseous metacarpal ligament (Lig. interosseum metacarpi), which often 

 undergoes more or less extensive ossification. 



