

Borders. The anterior border is concave, thin, and rough, and gives attachment 

 to the Deltoideus. The posterior border is convex, rough, thicker than the anterior, 

 arid gives attachment to the Trapezius. 



Medial Two-thirds. The medial two-thirds constitute the prismatic portion 

 of the bone, which is curved so as to be convex in front, concave behind, and is 

 marked by three borders, separating three surfaces. 



Borders. The anterior border is continuous with the anterior margin of the flat 

 portion. Its lateral part is smooth, and corresponds to the interval between the 

 attachments of the Pectoralis major and Deltoideus; its medial part forms the 

 lower boundary of an elliptical surface for the attachment of the clavicular portion 



Sternal extremity 



Acromial extremity 



FIG. 200. Left clavicle. Superior surface. 



of the Pectoralis major, and approaches the posterior border of the bone. The 

 superior border is continuous with the posterior margin of the flat portion, and 

 separates the anterior from the posterior surface. Smooth and rounded laterally, 

 it becomes rough toward the medial third for the attachment of the Sternocleido- 

 mastoideus, and ends at the upper angle of the sternal extremity. The posterior 

 or subclavian border separates the posterior from the inferior surface, and extends 

 from the coracoid tuberosity to the costal tuberosity; it forms the posterior boun- 

 dary of the groove for the Subclavius, and gives attachment to a layer of cervical 

 iascia which envelops the Omohyoideus. 



Articular capsule 





Inferior surface. 



Surfaces. The anterior surface is included between the superior and anterior 

 borders. Its lateral part looks upward, and is continuous with the superior sur- 

 face of the flattened portion; it is smooth, convex, and nearly subcutaneous, being 

 covered only by the Platysma. Medially it is divided by a narrow subcutaneous 

 area into two parts', a lower, elliptical in form, and directed forward, for the 

 attachment of the Pectoralis major; and an upper for the attachment of the 

 Sternocleidomastoideus. The posterior or cervical surface is smooth, and looks 

 backward toward the root of the neck. It is limited, above, by the superior 

 border; below, by the subclavian border; medially, by the margin of the sternal 

 extremity ; and laterally, by the coracoid tuberosity. It is concave medio-laterally, 



