286 



The Wrist Joint 



lage. It is an arthrodial joint, and is enclosed in a capsule consisting 

 of anterior, posterior, and lateral ligaments. The articular surfaces 



are covered with hyaline cartilage 

 and are lubricated by a synovial 

 membrane which is special to this 

 radio-carpal joint, though it is some- 

 times in communication with the 

 membrane of the inferior radio- 

 ulnar joint, as remarked above. 



The anterior ligament is at- 

 tached above to the anterior margin 

 of the radius and ulna, and below 

 to the front of the scaphoid, semi- 

 lunar, and cuneiform bones. The 

 posterior is a weaker band with 

 attachments very similar to those 

 just mentioned. The external 

 lateral ligament extends from the 

 tip of the styloid process of the 

 radius to the scaphoid, whilst the 

 internal passes from the tip of the 

 styloid process of the ulna to the 

 cuneiform and pisiform bones. 



Relations. In front of the joint 

 are the flexor tendons, an,d behind 

 are the extensor tendons. Over 

 the external lateral ligament the 

 radial artery winds, and close on the radial side of the flexor carpi 

 ulnaris are the ulnar nerve and artery. The median nerve is separated 

 from the anterior ligament by the flexor profundus. 



Supply. Branches of artery come from the anterior and posterior 

 carpal arches, the posterior interosseous, and the radial and ulnar. Its 

 nerves are branches of the ulnar and of the anterior and posterior inter- 

 osseous. 



Dislocations of the wrist are very rare, although the articulation 

 does not seem particularly secure ; injury is far more likely to expend 

 itself in fracturing the radius. In dislocation the first row of the carpal 

 bones may be carried on to the back or front of the radius and ulna, 

 beneath the extensor or flexor tendons. The luxation is easily recog- 

 nised and reduced. The backward dislocation may look at first sight 

 like a Colles's fracture (p. 282), but in the fracture the styloid process of 

 the radius is displaced upwards and backwards with the carpus, whilst 

 in the dislocation it remains in its proper place, and projects beneath 

 the skin. 



In opening a palmar abscess the scalpel must be used with great 

 caution, especially in the regions of the superficial and deep palmar 



13. 



Membrana sacciformis ; 3 and 4, lateral 

 ligaments ; 8, general synovial ravity 

 of intercarpal and carpo-metacarpal 

 joints ; 8', synovial bursa between unci- 

 form and fourth and fifth metacarpal 

 bones is often separate; 9', synovial 

 cavity of first carpo-metacarpal joint. 



(QUAIN.) 



