THE CLAVICLE. 691 



union of the superior and anterior costa is the anterior 

 angle, which contains the glenoid cavity. This cavity is 

 ovoidal, deepened hy the glenoid ligament, and is hroader 

 below than above. It is covered with cartilage, and has 

 the long head of the biceps arising from its superior mar- 

 gin. It articulates with the head of the humerus. Behind 

 this cavity the bone contracts, and is called the neck or 

 cervix. The inferior angle is formed by the junction of the 

 base and anterior costa ; it presents a flat surface for the 

 origin of the teres major. 



Structure. The scapula is composed of two compact 

 layers with cellular substance between them. The latter is 

 most abundant in the processes, while in the centre of the 

 dorsum the bone is diaphanous. Its development takes 

 place from several points, one for each of the processes, one 

 for the centre of the body, one for the base, and one for 

 the inferior angle. 



An ossific centre is noticed in the infra spinal fossa 

 about the seventh or eighth week, during the first year in 

 the coracoid process, at puberty in the acromion process, 

 in the fifteenth year at the inferior angle, during the 

 seventeenth or eighteenth year at the base, and about the 

 twentieth or twenty-fifth year the bone is found complete. 



THE CLAVICLE OR COLLAR BONE. 



The clavicle is situated transversely, between the upper 

 extremity of the ster- FIG. 216. 



num and the acro- 

 mion process of the 

 scapula. Its shape 

 is that of the italic s. 



It is longer in the female than the male, and consists of 

 a body and two extremities. The body is rather cylindri- 

 cal at the sternal, and flattened at the acromial end. Its 



FIG. 216 represents the Clavicle, a Anterior surface, b Point of attach- 

 ment of sterno-cleido mastoid muscle, c Sternal end of Clavicle, d Acro- 

 mial end. e Articular surface. / Where the conoid ligament is attached. 

 g Where the rhomboid ligament is attached. 



