106 PRACTICAL ANATOMY. 



conoid tubercle, which is directly above the coracoid 

 process and gives attachment to the conoid ligament. 

 Running outward and forward from the conoid tubercle 

 is the oblique line. The posterior border is rough and 

 convex ; the anterior border is rough and concave. The 

 inner two-thirds is prismoid in form and presents three 

 borders, anterior, posterior, and superior. The anterior, 

 continuous with the anterior border of the external 

 third, becomes indistinct toward the sternum. The pos- 

 terior or inferior border is a well-marked ridge, which 

 runs from the conoid tubercle to the rhomboid surface, 

 an elliptical surface at the under part of the sternal end 

 of the clavicle ; this border is well marked, and separates 



FIG. 49. THE LEFT CLAVICLE, UNDKR SURFACE. 



the posterior from the inferior part of the bone. The 

 superior border, continuous with the posterior border of 

 the flat portion, is rough near the sternal end, for the 

 origin of the stern o-mastoid muscle. These borders sep- 

 arate the three surfaces, anterior, posterior, and inferior. 

 The anterior surface is limited by the anterior and supe- 

 rior borders, and presents the nutrient foramen, which is 

 directed outward. The inferior surface is that surface 

 of the bone between the posterior and anterior borders. 

 It presents near the sternal extremity a triangular facet 

 for articulation with the first costal cartilage. Extemal 

 to this is the elliptical surface, slightly roughened for the 

 attachment of the rhomboid ligament, and passing out- 

 ward from the surface is the inferior border. The aero- 



