48 HUMAN ANATOMY. 



The inner two-thirds is prismatic and presents three surfaces 

 and three borders: 



Anterior surface, divided by line into upper rough surface 

 for sterno-mastoid muscle and lower for pectoralis major ; 



Posterior or cervical surface, gives attachment to sterno- 

 hyoid muscle and presents foramen for nutrient artery. 



Inferior or subclavian surface presents: 



Facet, continuous with sternal articular surface, for car- 

 tilage of first rib ; 



Rhomboid impression for costo-clavicular or rhomboid liga- 

 ment; 



Subclavian groove for attachment of subclavian muscle ; 



Longitudinal line, frequently dividing the groove into two 

 parts, for intermuscular septum of the muscle. 



Anterior border separates the anterior and posterior sur- 

 faces and limits the attachment of the pectoralis major. 



Superior border gives attachment to the sterno-mastoid 

 muscle. 



Posterior or subclavian border is short and concave, extend- 

 ing from the rhomboid impression to the conoid tubercle and 

 giving attachment to the subclavian fascia. 



The acromial extremity presents an oval facet for articula- 

 tion with the acromial process of the scapula and a rough circum- 

 ference for acromio-clavicular ligaments. 



The sternal extremity is triangular, and presents a facet for 

 cartilage of sternal articulation and rough circumference for 

 sterno-clavicular ligaments. 



The clavicle articulates with three bones the sternum, 

 scapula, and first costal cartilage. 



The muscular attachments are seven subclavius, platysma, 

 sterno-hyoid, sterno-mastoid, trapezius, pectoralis major, and del- 

 toid. 



Its ossific centres are two one each for body and sternal 

 end. 



THE SCAPULA, or shoulder-blade, is a large, flat, triangular 

 bone situated on the upper postero-lateral aspect of the thorax 

 from the second to seventh rib, inclusive. 



It consists of a body, head, neck, acromion, and coracoid 

 processes, and presents two surfaces, three borders, and three 

 angles. 



The anterior surface, or venter, presents : 



Subscapular fossa, a concave triangular surface for attach- 

 ment of subscapular muscles, marked by 



Oblique ridges, for the tendinous intersections of the muscle; 



Marginal surface, for attachment of serratus magnus; 



