270 



HEALTH AND DISEASE 



SCAPULO-HUMERAL OR SHOULDER-JOINT 



The shoulder-joint results from the union of the glenoid or shallow 

 cavity on the inferior extremity of the scapula or blade-bone, with the 



much larger articular surface provided 

 by the head of the humerus or upper 

 arm. 



This joint, although so large, pos- 

 sesses only one ligament, the capsular 

 (fig. 352), but it receives the support of 

 a number of muscles which pass over it 

 and are intimately connected with it. 



The shoulder-joint is capable of de- 

 scribing a great variety and consider- 

 able range of movement. It allows of 

 flexion, extension, abduction, adduction, 

 rotation, and circumduction. 



Fig. 352. Capsular Ligament of Shoulder-Joint 

 1, Scapula. 2, Humerus. 3, Capsular Ligament. 



HUMERO-RADIAL OR ELBOW- 

 JOINT 



Three bones are engaged in the for- 

 mation of this joint the humerus above, 

 the radius below, and the ulna behind. 

 It has two lateral ligaments passing from 

 the humerus to the radius. The outer 

 one is the stronger and shorter of the 

 two; the inner, the longer and smaller. 

 It has also a capsular ligament of con- 

 siderable extent, lined by synovial mem- 

 brane. It is essentially hinge-like in its 

 action, and admits only of movements of flexion and extension (fig. 353). 



Fig. 353. Humero-radial or Elbow-Joint 



1, Humerus. 2, Radius. 3, Olecranon process 

 of ulna. 4, Arciform ligament. 5, External 

 lateral ligament. 6, Anterior ligament. 



