LIGAMENTS OF THE WRIST AND METACARPUS. 



325 



Palmar fascia 

 Muscles of little finger 



Pisiform 



Anterior annular ligament 



Palmar carpal ligaments 



Tendon of flex, carpi rad. 



Scaphoid 



Cuneiform 



Unciform 



Os magnum 

 Dorsal carpal ligaments 



Transverse section through right wrist from above. The flexor tendons 

 have been removed from the canal beneath the annular ligament. 



Fig. 345. 



1\ 



Radius 



,t"-isi 





in frozen sections. Their broader bases are attached to the capsule, and the free 

 sh&rp edges end in the joint fitting in between the bones. 



TYi^ pisiform has a special joint on the palmar side of the cuneiform, with a lax 

 capsule. This is strength- 

 ened internally by a bundle Fig. 344. 

 from the cuneiform run- 

 ning from the dorsal to the 

 palmar side. Two well- 

 marked bands pass down- 

 ward from it on the latter 

 aspect ; the one to the base 

 of the fifth metacarpal is 

 really the end tendon of 

 the flexor carpi ulnaris, 

 the other passes obliquely 

 to the proximal edge of 

 the unciform process. 



The Anterior An- 

 nular Ligament. — This 

 is an extremely strong structure, bridging the hollow of the wrist, and enclosing a 

 canal through which pass the tendons of the long flexors of the thumb and fingers 

 and the median nerve. It springs internally from the process of the unciform and 



from the pisiform, the latter part being fused with 

 the band from it to the unciform. It is attached 

 externally to the ridge on the trapezium, and by a 

 deeper process to the tuberosity of the scaphoid 

 and to the inner side of the front surface of the 

 trapezium, thus splitting to allow the passage of 

 the tendon of the flexor carpi radialis through a 

 special canal in the groove of the trapezium. 

 Frozen sections through the wrist, passing through 

 the pisiform (Fig. 344) (but not those through the 

 unciform), show deep fibres from the annular liga- 

 ment passing down under the canal and blending 

 with the front of the capsular ligament of the 

 wrist. The proximal and distal borders of the 

 ligament are somewhat artificial, as it is connected 

 with the fascia of the forearm and with the palmar 

 fascia, besides receiving fibres from the flexor carpi 

 ulnaris. This anterior annular ligament holds the 

 sides of the wrist firmly together and prevents them 

 from spreading when pressure is applied from 

 above. Its fibres mingle with the origins of mus- 

 cles of the thumb and of the little finger. 



The posterior annular ligament is but a 

 thickening of the fascia of the back of the forearm, 

 and has no place among the true ligaments. 



The Carpo-Metacarpal Articulations. — 

 Those of the four inner fingers have been partially 

 described. They connect with the general articular 

 cavity of the wrist. A band from the adjacent 

 edges of the os magnum and unciform to those of 

 the third and fourth metacarpals (Fig. 340) does 

 not completely interrupt the continuity of this 

 cavity, as it does not reach the dorsal surface. 

 The carpus and metacarpus are connected on both 

 front and back by bands which can be fairly distinguished from the capsule. Trans- 

 verse bands run also on both surfaces from the base of one metacarpal to the 

 next. The opposed sides of the bases are partly covered with articular cartilage. 



Intra-articular disk 



Semilunar 



Intra-articular disk 



Os magnum 



ii;i"«^isrSS 



wS*' 









Third metacarpal 





m 



Frozen section through right middle finger, 

 the hand being straight. 



