1 8 THE SUPERIOR EXTREMITY 



and middle gleno-humeral ligaments, there is an opening in the 

 capsule. The synovial membrane of the joint herniates through 

 this opening to form a bursa, which is situated between the 

 subscapularis in front and the neck of the scapula and the 

 capsule behind. A similar bursa, communicating with the 

 joint, may occasionally be found between the capsule and the 

 tendon of the infra-spinatus. 



The long head of the biceps arises from the highest point on 

 the glenoid margin and traverses the joint. But although it 

 is intra-capsular, it remains extra-synovial as it receives a tubular 

 sheath from the synovial membrane (Fig. 6), which invests 

 the tendon for a varying distance after it has left the capsule. 

 This synovial sheath and the tendon are retained in the inter- 

 tubercular sulcus by the transverse ligament a special slip 

 of the capsule, which bridges the groove and is attached to 

 both tubercles. This ligament is occasionally torn by violent 

 muscular efforts,, and when that occurs the tendon of the biceps 

 becomes displaced to the medial side of the lesser tubercle. 

 Until the tendon is replaced by the movement of abduction,, 

 the forearm cannot be completely extended (Thomson and 

 Miles). 



The nerve-supply of the joint comes from the supra-scapular 

 and axillary (circumflex) nerves (C. 5 and 6). 



Around the surgical neck of the humerus an arterial ring 

 is formed by the anterior and posterior circumflex arteries, which 

 send branches proximally to supply the joint. These anastomose 

 with twigs from the transverse scapular (supra-scapular), which 

 descend from above, and with an ascending branch from the 

 (superior) profunda (p. 43). 



The presence of fluid within the joint may be appreciated 

 in the neighbourhood of the long head of the biceps, because 

 it gravitates down the synovial sheath which surrounds the 

 tendon. When the subscapularis bursa is involved, the swelling 

 may be felt high up on the posterior wall of the axilla. The 

 joint is best aspirated by pushing the needle backwards through 

 the deltoid and the subscapularis at a point a quarter of an inch 

 medial to the lesser tubercle, which serves as a convenient bony 

 landmark. In this way the great vessels and nerves and the 

 sub-acromial bursa are all avoided. 



Spread ot Tuberculous Disease in the Shoulder Region. 

 When tuberculous disease originates in the head or neck of the 

 scapula, it readily spreads to the joint through the articular 



