i2 4 THE SUPERIOR EXTREMITY 



The second constant aperture is that below the transverse 

 ligament of the humerus at the top of the intertubercular 

 sulcus. It is much smaller than the aperture in front, and 

 through it the tendon of the long head of the biceps, which 

 springs from the apex of the glenoid cavity, emerges from the 

 joint. The tendon is enclosed in a tubular prolongation of 

 the synovial stratum which surrounds it and lines the inter- 

 tubercular sulcus (Fig. 53). It is not often that a third 

 opening is found in the fibrous stratum. It is situated, when 

 present, in the postero- lateral part of the capsule and 

 permits the protrusion of the synovial stratum to form a bursa 

 under cover of the infraspinatus muscle (Fig. 52). Still 

 more rarely the subacromial bursa communicates with the 

 cavity of the joint through an opening which is situated 

 between the supraspinatus and subscapularis muscles. 



In four situations the fibrous stratum of the capsule is 

 thickened by longitudinal bands of fibres which pass from 

 the scapula to the humerus. One of the thickenings, the 

 coraco-humeral ligament, can be seen from the exterior; the 

 other three, the gleno-humeral ligaments^ are thickenings of 

 the inner surface of the fibrous stratum of the capsule and 

 can be seen only from the interior of the joint. 



Ligamentum Coracohumerale. The coraco-humeral liga- 

 ment is placed upon the superior aspect of the joint. It is 

 a broad band of great strength, which is more or less com- 

 pletely incorporated with the capsule. Proximally, it is fixed 

 to the root and lateral border of the coracoid process of the 

 scapula, and it passes thence, obliquely distally and laterally, 

 to gain attachment to the two tubercles of the humerus, and 

 to the transverse humeral ligament, which forms a strong arch 

 over the upper part of the intertubercular sulcus. 



Ligamenta Glenohumeralia. There are three gleno- 

 humeral ligaments. To see them the posterior part of the 

 capsule must be divided by a vertical incision and the head 

 of the humerus must be turned aside or removed. The 

 superior gleno-humeral ligament springs from the margin of 

 the glenoid cavity immediately anterior to the tendon of the 

 long head of the biceps brachii, and it passes to a small 

 pit situated on the proximal extremity of the humerus close 

 to the top of the intertubercular sulcus. The middle gleno- 

 humeral ligament is attached to the scapula immediately 

 above the notch on the anterior margin of the glenoid cavity, 



