EL BOW JOINT, 121 



which is attached around the margin of the glenoid cavity for the 

 purpose of protecting its edges, and deepening its cavity. It divides 

 superiorly into two slips which are continuous with the long tendon 

 of the biceps ; hence the ligament is frequently described as being 

 formed by the splitting of that tendon. The cavity of the articu- 

 lation is traversed by the long tendon of the biceps which is 

 enclosed in a sheath of synovial membrane in its passage through 

 the joint. 



The synovial membrane of the shoulder joint is very extensive ; it 

 communicates anteriorly through an opening in the capsular liga- 

 ment with a large bursal sac, which lines the under surface of the 

 tendon of the subscapularis muscle. Superiorly, it frequently com- 

 municates through another opening in the capsular ligament with 

 a bursal sac belonging to the infra-spinatus muscle ; and it more- 

 over forms a sheath around that portion of the tendon of the biceps, 

 which is included within the joint. 



The muscles immediately surrounding the shoulder joint are the 

 subscapularis, supra-spinatus, infra-spinatus, teres minor, long head 

 of the triceps, and deltoid ; the long tendon of the biceps is within 

 the capsular ligament. 



Actions. The shoulder joint is capable of every variety of motion, 

 viz. of movement forwards and backwards, of abduction, and adduc- 

 tion, of circumduction and rotation. 



5. Elbow Joint The elbow is a ginglymoid articulation; its 

 ligaments are four in number : 



Anterior, 



Posterior, 



Internal lateral, 



External lateral. 



The anterior ligament is a broad and thin membranous layer, 

 descending from the anterior surface of the humerus, immediately 

 above the joint, to the coronoid process of the ulna and orbicular 

 ligament. On each side it is connected with the lateral ligaments. 

 It is composed of fibres which pass in three different directions, 

 vertical, transverse, and oblique, the latter being extended from 

 within outwards to the orbicular ligament, into which they are 

 attached inferiorly. This ligament is covered in by the brachialis 

 anticus muscle. 



The posterior ligament is a broad and loose fold passing between 

 the posterior surface of the humerus and the anterior surface of the 

 base of the olecranon, and connected attach side with the lateral 

 ligaments. It is covered in by the tendon of the triceps. 



The internal lateral ligament is a thick triangular layer, attached 

 above, by its apex, to the internal condyle of the humerus ; and 

 below, by its expanded border, to the margin of the greater sig- 

 moid cavity of the ulna, extending from the coronoid process to 

 the olecranon. At its insertion it is intermingled with some trans- 



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