AETICULATIUXS OF THE HAND. 



1.37 



likewise two processes between the three bones of the first row, and 

 three between the four bones of the second. It is further continued 

 downwards into the inner four carpo-metacarpal and three intermeta- 

 carpal articulations. In some rare cases there is continuity with the 

 synovial membrane of the wrist-joint, by deficiency of one of the 

 interosseous ligaments between the carpal bones. 



The pisiform bone is articulated by a fibrous capsule and synovial 

 membrane with the cuneiform bone. Inferiorly it is united by two 

 strong ligaments with the unciform and fifth metacarpal bones, and is 

 sometimes also connected with other metacarpal bones ; superiorly it 

 receives the tendon of the flexor carpi ulnaris muscle. The synovial 

 cavity is usually distinct, but sometimes communicates with that of the 

 radio-carpal articulation. 



The anterior annular ligament of the wrist is a strong and 

 thick band, which extends from the prominences made by the trapezium 

 and scaphoid bone on the radial side of the carpus, directly across to the 

 pisiform bone and unciform process, and converts the transverse arch of 

 the carpus into a ring through which the flexor tendons of the digits 

 pass into the hand. 



The posterior annular ligament, placed at the back of the wrist, 

 is only a thickened part of the aponeurosis of the forearm. It extends 

 from the lower part of the radius, at its outer border, to the inner part 

 of the cuneiform and pisiform bones and serves to bind down the 

 extensor tendons. 



CAKPO-METACAEPAL AND INTERMETACARPAL ARTICULATIONS 



Fig. 143. — General view of the Articulations °' 



OF THE Wrist and Hand from before. 3 



1, lower iiart of the interosseous membrane ; 2, 

 and from that i)oint across the lower end of the 

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

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

 form ; 7, OS magnum, witli most of the deeper 

 ligaments uniting these bones ; I, first metacarpo- 

 phalangeal articulation with its external lateral 

 ligament ; H to V, ti-ausverse metacari^al liga- 

 ment : in the several phalangeal articulations the 

 lateral ligaments are shown ; in the first the 

 external only is visible. 



The four inner metacarpal bones 



are bound together at their distal ex- 

 tremities by thin fibres passing between 

 them on their palmar aspect, and consti- 

 tuting the transi'crse Uijament. 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 meta- 

 carpal bones with the carpus, each having two sucli ligaments 



expect 



