THE SKELETON. 



53 



A slight constriction between the base of the spine and 

 the margin of the glenoid cavity is termed the neck. From, 



FIG. 30. LATERAL OR OUTER ASPECT OF THE SCAPULA. 



ac, Acromion process; ax, axillary border; c, coracoid process; gi, 

 glenoid cavity ; m, metacromion process ; sc, suprascapular notch ; 

 sp, spine ; sup. fos, supraspinous fossa ; vr, vertebral border ; n, neck. 



the cranial side of the latter the coracoid process curves 

 mediad. 



The clavicle is a slender 

 curved bone, about one inch 

 long, imbedded in the mus- 

 cle between the manubrium FlG . 3I ._CAUDAL ASPECT OF LEFT 



CLAVICLE. 



b, Medial end ; a, lateral end. 



and the coracoid process 

 (Fig. 21 ). It does not ar- 

 ticulate with any bone, but is held in place by the cephalo- 

 humeral and cleidomastoid muscles (Fig. 48). 



The shoulder girdle varies somewhat among the Mam- 

 malia. The clavicle is never fully developed in any of the 

 Carnivora. Primates, Chiroptera, Edentata, and Monotre- 

 mata are the only orders in which all the species possess 

 clavicles. A third element of the shoulder girdle, known as 

 the coracoid, is a fully developed bone only in the Monotre- 



