256 



HUMAN ANATOMY. 



back. With the arm at the side, the superior angle is about on the level of the 

 upper edge of the second rib ; the inferior angle is opposite the seventh intercostal 

 space (and hence is a guide in selecting a space for the various operations for em- 

 pyema, page 1867); the inner end of the spine is opposite the spinous process of the 

 third dorsal vertebra. 



With the shoulders drawn forcibly backward, the vertebral borders of the scapulae 

 can be made almost to touch at the level of the spines, and are not more than from 

 two to three inches apart at the angles. With the hands clasped on the vertex, the 

 inferior angles are from sixteen to seventeen inches apart. By crossing the arms on 

 the front of the chest, and leaning forward, the scapulae are also widely separated, 

 and this position is therefore selected for auscultation and percussion. 



The mobility of the scapula lessens the functional disability in ankylosis of the 

 shoulder-joint. 



LIGAMENTS OF THE SCAPULA. 



Two ligaments — the transverse and the coraco-acromial — pass from one part of the 

 scapula to another. 



The transverse or suprascapular ligament ' (Fig. 289) is a little band on the 

 upper border, just behind the root of the coracoid, making a bridge over the supra- 

 scapular notch, under which the suprascapular nerve passes. It may be replaced by 

 bone. 



The coraco-acromial ligament- (Fig. 274) is a triangular structure, broad 

 at its base, along the outer border of the coracoid process, and narrowing to its 

 insertion into the inner side of the end of the acromion just in front of the acromio- 

 clavicular joint. The borders are strong, converging bands with a weak space 

 between, the front one being the stronger and overlapping the other when they 



Fig. 274. 



Capsule of shoulder-joint 

 Humerus--^ 



Tendon of biceps --_A- 

 Coraco-acromial ligament 



Coracoid process 

 Coraco-clavicular ligament 



Acromio-clavicular joint 



Acromion 



Clavicle 



Ligaments about the right shoulder from above. 



meet. The course of the fibres in the weaker part is variable ; sometimes they 

 diverge from near the front of the coracoid to the posterior band, sometimes they 

 are in the main parallel with the latter, sometimes a band passes from this membrane 

 to the front of the clavicle. The weak portion of this ligament is pierced by the 

 pectoralis minor, when, as often happens, this muscle is inserted into the capsule of 

 the shoulder or the upper end of the humerus. This ligament is really part of the 

 apparatus of the shoulder-joint, forming a roof over the capsule, from which it is 

 separated by a bursa. Before dissection the hind border of the ligament is not very 



' LIb. transversom scapulae sttperius. - Lig. corpcracromiale. 



