78 HUMERUS. 



coracoid process and body takes place during the fifteenth year ; the 

 bone is not complete till manhood. 



Articulations. With the clavicle and humerus. 



Attachment of Muscles. To sixteen ; by its anterior surface to the 

 subscapularis ; posterior surface, supra-spinatus and infra-spinatus ; 

 superior border, omo-hyoid ; posterior border, levator anguli scapulae, 

 rhomboideus minor, rhomboideus major, and serratus magnus ; anterior 

 border, long head of the triceps, teres minor, and teres major; upper 

 angle of the glenoid cavity, to the long tendon of the biceps ; spine 

 and acromion, to the trapezius and deltoid ; coracoid process, to the 

 pectoralis minor, short head of the biceps, and coraco-brachialis. 

 The ligaments attached to the coracoid process are, the coracoid, 

 coraco-clavicular, and coraco-humeral, and the costo-coracoid mem- 

 brane. 



HUMERUS. The humerus is a long bone divisible into a shaft and 

 two extremities. 



The superior extremity presents a rounded liead ; a constriction im- 

 mediately around the base of the head, the neck ; a greater and a lesser 

 tubernsity. The greater tuberosity is situated most externally, and is 

 separated from the lesser by a vertical furrow, the bicipital groove, 

 which lodges the long tendon of the biceps. The edges of this groove 

 below the head of the bone are raised and rough, and are called the 

 anterior and posterior bicipital ridge ; the former serves for the in- 

 sertion of the pectoralis major muscle, and the latter of the latissimus 

 dorsi and teres major. . 



The constriction of the bone below the tuberosities is the surgical 

 neck, and is so named, in contradistinction to the true neck, from be- 

 ing the seat of the accident called by surgical writers fracture of tJie 

 neck of the humerus. 



The shaft of the bone is prismoid at its upper part, and flattened 

 from before backwards below. Upon its outer side, at about its 

 middle, is a rough triangular eminence, which gives insertion to the 

 deltoid ; and immediately on each side of this eminence is a smooth 

 depression, corresponding with the two heads of the brachialis anticus. 

 Upon the inner side of the middle of the shaft is a ridge, for the at- 

 tachment of the coraco-brachialis muscle ; and behind, an oblique and 

 shallow groove, which lodges the musculo- spiral nerve and superior 

 profunda artery. The foramen for the medullary vessels is situated 

 upon the inner surface of the shaft of the bone a little below the 

 coraco-brachial ridge ; it is directed downwards. 



The lorcer extremity is flattened from before backwards, and is ter- 

 minated inferiorly by a long articular surface, divided into two parts 

 by an elevated ridge. The external portion of the articular surface is 

 a rounded protuberance, eminenlia capitata, which articulates with the 

 cup-shaped depression on the head of the radius ; the internal portion 

 is a concave and pulley-like surface, trochlea, which articulates with 

 the ulna. Projecting beyond the articular surface on each side are 



