88 TOPOGRAPHIC AND APPLIED ANATOMY. 



extensor tendons are not continued into the fingers, tenosynovitis occurs much more rarely upon 

 the dorsal than upon the palmar surface. 



The following articulations may be differentiated at the wrist: 



1. The radiocarpal articulation or wrist- joint, between the radius and the distal surface of 

 the interarticular fibrocartilage on one side, and the scaphoid, semilunar, and cuneiform bones 

 upon the other. 



2. The inferior radio-ulnar articulation between the sigmoid cavity of the radius and the head 

 of the ulna. This joint is completely separated from the preceding one. 



3. (a) The inter car pal articulations, between the carpal bones; (b) the carpometacarpal 

 articulations, between the second row of the carpal bones and the metacarpal bones; (c) the 

 intermetacarpal articulations, between the lateral articular surfaces of trie bases of the metacarpal 

 bones. These three sets of articulations usually possess a common synovial membrane; the 

 carpal bones are joined together by the tense interosseous ligaments. The synovial cavity of the 

 joint between the unciform and the fourth and fifth metacarpal bones is occasionally separated 

 from the large synovial cavity of the carpus. 



4. The articulation between the pisiform and the cuneiform bones. 



5. The articulation of the metacarpal bone of the thumb with the trapezium (saddle-joint). 

 In disarticulating at this joint care must be taken to avoid injuring the articulation between the 

 trapezium and the second metacarpal bone, as such an injury would open up the common synovial 

 cavity of the carpus. 



The following ligaments should be noted : 



1. The external lateral ligament, from the styloid process of the radius to the scaphoid bone. 



2. The internal lateral ligament, from the styloid process of the ulna to the cuneiform bone. 



3. The anterior ligament, in front of the wrist- joint, from the lower end of the radius to the 

 scaphoid, semilunar, and cuneiform bones and to the os magnum. 



4. The posterior ligament, behind the wrist-joint, from the lower end of the radius to the 

 scaphoid, semilunar, and cuneiform bones. 



5. The ligamentum carpi radiatum, on the anterior surface of the carpus, which connects 

 the os magnum with the surrounding bones. 



A transverse section of the finger recalls the fact that the tendons of the superficial and deep 

 flexors run in a common sheath upon the palmar surface, and that there is no such sheath upon 

 the dorsal surface. Upon the back of the finger the extensor tendon becomes continuous with 

 the dorsal aponeurosis. The larger vessels and nerves are situated upon the palmar surface, 

 while the smaller ones are upon the dorsal surface. The nerves of the palmar surface are nearer 

 the median line of the finger than the digital arteries, which anastomose freely at the pulp of the 

 finger. The palmar nerves of the fingers also supply the dorsal surfaces of the terminal phalanges, 

 which are not reached by the small dorsal nerves. 



QUESTIONS. 



Beneath what portion of the clavicle does the subclavian artery pass ? 



What important structures may be compressed in a fracture of the clavicle or of the neck of the 

 humerus or bv a subcoracoid dislocation of the shoulder? 



