ARTICULATIONS OF THE SHOULDER. 



247 



Fig. 55.* The glenoid cavity of the scapula, 



which is so small in the dried bone", 

 when compared with the head of 

 the os humeri, is enlarged lay the 

 long tendon of the biceps muscle, 

 which is attached to the upper edge 

 of its margin, and then divides and 

 passes down on each side of the 

 cavity, increasing the breadth of it 

 considerably, thus forming what is 

 called iheglenoid ligament, deepen- 

 ing the socket, and giving greater 

 latitude of motion to the arm, from its 

 elasticity, than if the socket had all 

 been formed of bone. It appears to be blended with the carti- 

 lage that lines the cavity, and also with the capsular ligament 

 which is exterior to it. 



The .articulating surface, thus composed, is perfectly regular 

 and uniform. 



The synovial , ligament, in this articulation, is so blended 

 with an external stronger ligament, that it cannot be separated 

 in the recent subject ; but, notwithstanding, it is applied to the 

 articulating surfaces in the same way that it is applied to the 

 other joints forming a capsule. The stronger exterior lamina 

 is, of course, only applied to that part of the synovial capsule 

 which proceeds from the margin of one cartilaginous articulating 

 surface to the other : it appears to be most intimately connected 

 with the periosteum, and is rendered more firm and thick in 

 particular parts, by the addition of fibres from the tendons of the 

 supra and infra-spinatus, and subscapularis 'muscles with which 

 it is blended. 



It arises from the scapula at a small distance from the mar- 



* The ligaments of the scapula and shoulder joint. 1. The superior acromio- 

 clavicular ligament. 2. The coraco-clavicular ligament ; this aspect of the 

 ligament is named trapezoid. 3. The coraco-acromial ligament. 4. Coracoid 

 or transverse ligament as it is sometimes called. 5. Capsular ligament. 6. 

 Coraco-humeral ligament. 7. The long tendons of the biceps issuing from the 

 capsular ligament, and entering the bicipital groove. 



