THE SHOULDER-JOINT 133 



by the infraspinatus and teres minor, below by the long head 

 of the triceps, and internally by the subscapularis. There 

 is a weak place in the capsule uncovered by muscle between 

 the edges of the teres major and subscapularis; vessels and 

 nerves enter here. 



The superficial fibers of the capsule are longitudinal, and 

 deeper ones are circular, forming a truncated cone, with its 

 narrow end toward the scapula. Below are folds in the capsule 

 which become straight in raising the arm; 



The glenoid ligament is a fibrocartilaginous rim attached 

 to the margin of the glenoid fossa to form a deeper cavity; 

 it is triangular on section, and ^V mcn (3 mm.) broad at its 

 base. It is partly formed by the biceps tendon above as it 

 bifurcates at its attachment, and by the triceps below, the 

 fibers being arranged in concentric rings. Its intrinsic fibers 

 are fused with the capsule. 



The synovial membrane lines the capsule and covers the outer 

 side of the glenoid ligament, and is continued a short distance 

 over the cartilage on the head of the humerus. The long tendon 

 of the biceps passing through the capsule is enclosed in a tubular 

 sheath of synovial membrane, and so does not really enter the 

 synovial cavity. A rounded protrusion of the synovial mem- 

 brane, bursa intertubcrcularis, clothes the upper part of the 

 bicipital groove as far as the insertion of the pectoralis major 

 and latissimus dorsi. From within the tube of synovial mem- 

 brane there passes to the tendon of the biceps a retinaculum 

 of longitudinal bundles of connective tissue. 



The joint cavity communicates with a large bursal sac 

 beneath the subscapularis tendon, and occasionally with that 

 under the tendon of the infraspinatus muscle. 



The deltoid muscle is. separated from the capsule by a large 

 bursa which does not communicate with the joint. 



Among the strengthening bands of the capsule is the coraco- 

 humeral ligament, rising from the outer border of the coracoid, 

 spreading out upon the upper and posterior wall of the capsule, 

 and inserted into the great tuberosity of the humerus. 



The ligamentum coracoglenoidale is a part of the coraco- 

 humeral, rising with it and passing backward and outward at 

 right angles on the surface of the capsule to the upper margin 

 of the glenoid cavity. 



