METACAKPAL AND PHALANGEAL ARTICULATIONS. 



U5 



aspect, the transverse ligament. At their proximal extremities they are 

 united to one another and to the carpal bones in articulations, the common 

 synovial lining of which is derived from that of the carpal joint. In these 

 articulations the four metacarpal bones are bound together by three dorsal, 

 and three palmar, and by strong interosseous ligaments. There are also 

 dorsal ligaments uniting these metacarpal bones with the carpus, each having 

 two such ligaments except the fifth. Thus to the second, or that of the fore- 

 finger, a thin fasciculus of fibres passes from the trapezium, and another 

 from the trapezoid bone ; the third receives one from the trapezoid, and 

 from the os magnum; the fourth from the os magnum and also from the 

 unciform ; but the fifth is connected with the unciform only. The palmar 

 ligaments are not so well defined ; there is a single band to each bone, 

 except that of the little finger. There is likewise an interosseous band in 

 one part of the carpo-metacarpal articulation, connecting the lower and 

 contiguous angles of the os magnum and unciform to the adjacent angle of 

 the third metacarpal bone. This ligament is usually surrounded by a part 

 of the general synovial membrane, but sometimes it separates the cavity be- 

 tween the unciform and two inner metacarpal bones from the rest of the joint. 

 The first metacarpal bone is unconnected with the others, and is articu- 

 lated with the trapezium by an external and an internal ligament, a capsular 

 investment, and a distinct synovial membrane. 



ARTICULATIONS OF THE METACARPAL BONES WITH THE PHALANGES, AND OP 

 THE PHALANGES WITH EACH OTHER. 



Fig. 134. 



The rounded head of each of the last 

 four metacarpal bones, being received inta 

 the slight concavity in the extremity of 

 the first phalanx, is maintained in its 

 position by two lateral ligaments, an an- 

 terior ligament, and a synovial mem- 

 brane. 



The lateral ligaments consist of dense 

 and thick fasciculi of fibres, placed one at 

 each side of the joint ; they are attached 

 each by one extremity to the side of the 



Fig. 134. GENERAL VIEW OP THE ARTICULATIONS 



OF THE WRIST AND HAND FROM BEFORE. 



1, lower part of the interosseous membrane ; 2, 

 and from that point across the lower end of the 

 radius, the palmar radio-carpal ligaments ; 3, sca- 

 phoid bone ; 4, pisiform ; 5, trapezium ; 6, unci- 

 form ; 7, os magnum, with most of the deeper 

 ligaments uniting these bones ; I, first metacarpo- 

 phalangeal articulation with its external lateral 

 ligament; II to V, transverse metacarpal liga- 

 ment : in the several phalangeal articulations the 

 lateral ligaments are shown ; in the first the 

 external only is visible. 



metacarpal bone, and by the other to the 

 anterior ligament and the contiguous ex- 

 tremity of the phalanx. The direction of 

 the fibres is downwards and forwards. 



The anterior or palmar ligament, or rather fibrous plate, occupies the 

 interval between the lateral ligaments on the palmar aspect of each joint ; it 



