ARTICULATION OF THE WRIST. 



253 



Fig. 60 * 



Another ligament, (external lateral,) on the external side, 

 arises from the styloid process of the radius, and is inserted into 

 the scaphoides, some of its fibres being continued into the 

 aforesaid transverse ligament, and the trapezium. 



There are two broad irregular ligamentous membranes : one 

 of which arises from the anterior margin of the articulating 

 surface of the radius ; and the other from the posterior margin. 

 One of them is inserted anteriorly, and the other posteriorly, 

 into the margin of the corresponding surface of the scaphoides, 

 lunare and cuneiforme. They adhere to the synovial membrane ; 

 but in some places this membrane appears through apertures 

 which are in them. 



The surfaces, by which the 

 first and second rows of carpal 

 bones are articulated with each 

 other, are very irregular. The 

 magnum and part of the unci- 

 forme form a prominent oblong 

 head ; on each side of which is 

 a much lower surface, formed 

 by the trapezium and trapezoides 

 externally, and the remaining por- 

 tion of the unciforme internally .f 

 The scaphoides, lunare, and 

 cuneiforme, form a cavity which 

 corresponds with this head, and 

 also with the lower surface 



* A diagram showing the disposition of the five synovial membranes of the 

 wrist joint. 1. The sacciform membrane. 2. The second synovial membrane. 

 3, 3. The third, or large synovial membrane. 4. The synovial membrane be- 

 tween the pisiform bone and the cuneiforme. 5. The synovial membrane of 

 the metacarpal articulation of the thumb. 6. The lower extremity of the radius. 

 7. The lower extremity of the ulna. 8. The interarticular fibro-cartilage. S. 

 The scaphoid bone. L. The semilunare. C. The cuneiforme ; the interosseous 

 ligaments are seen passing between those three bones and separating the articu- 

 lation of the wri.st (2) from the articulation of the carpal bones (3). P. The 

 pisiforme. T. The trapezium. 2T. The trapezoides. M. The os magnum. 

 U. The unciforme ; interosseous ligaments are seen connecting the os magnum 

 with the trapezoides and unciforme. 9. The base of the metacarpal bone of the 

 thumb. 10, 10. The bases of the other metacarpal bones. 



f The palm of the hand is supposed to present forward. 



22 



