WRIST JOINT. 



155 



radius presents a concavity which moves upon the rounded head of the 

 ulna. The movements of the radius are chiefly limited by the anterior 

 and posterior inferior ligaments, hence these are not unfrequently ruptured 

 in great muscular efforts. 



7. Wrist Joint. The wrist is a ginglymoid articulation ; the articular 

 surfaces entering into its formation being the radius and under surface of 

 the triangular fibro-cartilage above, and the rounded surfaces of the 

 scaphoid, semilunar, and cuneiform bone below; its ligaments are four 

 in number, 



Anterior, Internal lateral, 



Posterior, External lateral. 



The anterior ligament is a broad and mem- Fj g . oo. 



branous layer consisting of three fasciculi, which 

 pass between the lower part of the radius and 

 the scaphoid, semilunar, and cuneiform bone. 



The posterior ligament, also thin and loose, 

 passes between the posterior surface of the ra- 

 dius, and the posterior surface of the semilunar 

 and cuneiform bone. 



The internal lateral ligament extends from 

 the styloid process of the ulna to the cuneiform 

 and pisiform bone. 



The external lateral ligament is attached by 

 one extremity to the styloid process of the ra- 

 dius, and by the other to the side of the scaphoid 

 bone. The radial artery rests on this ligament 

 as it passes backwards to the first metacarpal 

 space. 



The synovial membrane of the wrist joint 

 lines the under surface of the radius and inter- 

 articular cartilage above, and the first row of 

 bones of the carpus below. 



The relations of the wrist joint are the flexor 

 and extensor tendons by which it is surrounded, and the radial and ulnar 

 artery. 



Actions. The movements of the wrist joint are flexion, extension, ad- 

 duction, abduction, and circumduction. In these motions the articular 

 surfaces glide upon each other. 



* The ligaments of the anterior aspect of the wrist and hand. 1. The lower part of 

 the interosseous membrane. 2. The anterior inferior radio-ulnar ligament. 3. The an- 

 terior ligament of the wrist joint. 4. Its external lateral ligament. 5. Its internal 

 lateral ligament. 6. The palmar ligaments of the carpus. 7. The pisiform bone with 

 its ligaments. 8. The ligaments connecting the second range of carpal bones with the 

 metacarpal and the metacarpal with each other. 9. The capsular ligament of the carpo 

 metacarpal articulation of the thumb. 10. Anterior ligament of the metacarpo-pha- 

 langeal articulation of the thumb. 11. One of the lateral ligaments of that articulation. 

 12. Anterior ligament of the metacarpo-phalangeal articulation of the index finger; this 

 ligament has been removed in the other fingers. 13. Lateral ligaments of the same 

 articulation ; the corresponding ligaments are seen in the other articulations. 14. Trans- 

 verse ligament connecting the heads of the metacarpal bones of the index and middle 

 fingers : the same ligament is seen between the other fingers. 15. Anterior and one 

 lateral ligament of the phalangeal articulation of the thumb. 16. Anterior and lateial 

 ligaments of the phalangeal articulations cf the index finger; the anterior ligaments are 

 removed in the other fingers. 



