SUPERFICIAL DISSECTIONS ii 



tinuation of the posterior common ligament of the knee, and becomes 

 united to the tendon of the flexor perforans about three and a half 

 inches below the carpus. Along its outer edge is seen to run the 

 external metacarpal vein (32). 



The Muscles and Tendons 



The Supraspinatus Muscle (6). — This occupies the whole of the 

 fossa in front of, or above the spine of the scapula, which bears the 

 same name. Its outer tendon of insertion, which is attached to the 

 summit of the external tuberosity of the humerus, is represented in 

 the plate (12). The muscle is a powerful extensor of the shoulder 

 joint, and is supplied by the suprascapular nerve. 



The Infraspinatus Muscle (5). — Occupies almost the whole of the 

 infraspinous fossa. The outer surface of the muscle presents a 

 depression which runs obliquely downwards and forwards, and 

 which is somewhat deceptive in suggesting the possession of two 

 bellies. 



It is inserted by an inner tendon into the convexity of the 

 external tuberosity of the humerus and by an outer broad tendon (8), 

 which is represented in the plate, into the upper portion of the 

 deltoid ridge. This muscle is an abductor and outward rotator of 

 the humerus, and is supplied by the suprascapular nerve. 



The Deltoid Muscle (9). — This muscle is also traversed obliquely 

 downwards and forwards by a depression in which the scapular fascia 

 dips. It arises from the dorsal angle and part of the posterior 

 border of the scapula, and also from the scapular fascia. It is 

 inserted into the deltoid tubercle. Its action is similar to that of 

 the infraspinatus, and it is supplied by the circumflex nerve. 



The Biceps (16). — In front of the upper half of the humerus we 

 find the biceps muscle, which is seen to arise from the coracoid 

 process. Its tendon passes through the bicipital groove between the 



