THE SHOULDER REGION 13 



A sub-coracoid centre,, which forms part of the base of the 

 coracoid and the upper part of the glenoid cavity, appears at 

 ten and fuses at seventeen. The margin of the glenoid cavity 

 inferiorly is formed by a secondary centre which appears at 

 seventeen and fuses soon after. The other secondary centres 

 have little surgical importance. 



Fractures of the Scapula are uncommon because the bone 

 is well protected by muscles. The commonest variety is 

 fracture of the body, generally through the infra-spinous fossa. 

 The spine and coracoid process, which belong to the upper 

 fragment, may be gripped with one hand, and the inferior 

 angle, which belongs to the lower fragment, with the other. 

 Preternatural mobility and crepitus may be determined by 

 moving the hands in opposite directions. 



If the surgical neck, which extends from the scapular notch 

 to a point on the axillary border just below the glenoid cavity, 

 is fractured, the surgeon can grasp the spine and acromion with 

 one hand and the head of the humerus with the other. Crepitus 

 may sometimes be elicited, through the medium of the capsule 

 of the shoulder-joint, by moving the head of the humerus 

 backwards and forwards. 



Fracture of the Coracoid is rare, and up to seventeen may 

 l)e of the nature of a separation of the epiphysis. There is little 

 displacement, unless the coraco -clavicular ligament, which 

 holds it up, is torn. Laterally, the coracoid is steadied by the 

 coraco-acromial ligament, and medially, by the pectoralis minor. 

 It is drawn downwards by the weight of the arm and by the 

 coraco-brachialis and the short head of the biceps, which are 

 attached to its tip. 



In complete excision of the scapula for malignant disease, a 

 preliminary ligature of the subscapular vessels and myotomy 

 of the muscles attached to the coracoid process may be performed 

 through an incision along the medial border of the coraco- 

 brachialis. 



The Coraco-Acromial Ligament passes from the lateral 

 border of the coracoid process to the acromion just in front of 

 the acromio-clavicular joint. It forms a strong arch above 

 the shoulder-joint, and helps to prevent upward dislocation of 

 the head of the humerus. 



The Sub-acromial Bursa lies between the deltoid, the 

 acromion and the coraco-acromial ligament above, and the 

 capsule of the shoulder-joint and the muscles attached to it 



