120 



SHOULDER JOINT. 



synovia! membranes are very delicate. There is only one, when the 

 fibro-cartilage is incomplete. 



Actions. The acromio-clavicular articulation admits of two move- 

 ments, the gliding of the surfaces upon each other ; and the rotation 

 of the scapula, upon the extremity of the clavicle. 



3. The Proper ligaments of the Scapula are the 



Coraco-acromial, 

 ^ Transverse. 



The coraco-acromial ligament is a broad and thick triangular 

 band, which forms a protecting arch over the shoulder joint. It is 

 attached by its apex to the point of the acromion process, and by 

 its base to the external border of the coracoid process its whole 

 length. This ligament is in relation above with the under surface 

 of the deltoid muscle ; and below with the tendon of the supra-spi- 

 natus muscle, a bursa mucosa being usually interposed. 



The transverse or coracoid ligament is 

 Fig. 53 * a narrow but strong fasciculus which 



crosses the notch in the upper border of 

 the scapula, from the base of the cora- 

 coid process, and converts it into a fora- 

 men. The supra-scapular nerve passes 

 through this foramen. 



4. Shoulder Joint. The scapulo-hume- 

 ral articulation is an enarthrosis, or ball 

 and socket joint its ligaments are, the 

 Capsular, 

 Coraco-hmneral, 

 Glenoid. 



The capsular ligament completely en- 

 circles the articulating head of the sca- 

 pula and the head of the humerus, and is 

 attached to the neck of each bone. It is 

 thick above, where resistance is most 

 required, and is strengthened by the tendons of the supra-spinatus, 

 infra-spinatus, teres minor, and subscapularis muscles : below it is 

 thin and loose. The capsule is incomplete at the point of contact 

 with the tendons, so that they obtain upon their inner surface a 

 covering of synovial membrane. ' 



The coraco-humeral ligament is a broad band which descends 

 obliquely outwards from the border of the coracoid process to the 

 greater tuberosity of the humerus, and serves to strengthen the 

 superior and anterior part of the capsular ligament. 



The glenoid ligament is the prismoid band of fibro-cartilage, 



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

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

 trapezoid. 3. The coraco-acromial ligament. 4. The transverse ligament. 5. The 

 capsular ligament. 6. The coraco-humeral ligament. 7. The long tendon of the 

 biceps issuing from the capsular ligament, and entering the bicipital groove. 



