74 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM 



sternum, are called sternal, true, or vertebrostemal ribs; the 

 remaining five pairs are asternal or false ribs ; each of the upper 

 three pairs of false ribs has its cartilage attached to the cartilage 

 above it, vertebrochondral; the last two pairs have no such 

 attachment, and are floating or vertebral ribs. 



Each rib presents three parts a body, an anterior and a 

 posterior extremity. 



The posterior extremity presents for examination a head, 

 a neck, and a tuberosity. The head is thickened and rough; 

 it has a superior and an inferior articular facet for articulation 

 with two vertebrae; the lower is the larger; between them is 

 a ridge for the attachment of the interarticular ligament. 



FIG. 13 



n'or anterior costo-transvcrse ligament. 



Facet for body of ^_ 4~- _ For posterior costo-transverse ligament. 



upper dorsal vertebra.. 



Ridge for inter-, 

 articular ligament . 



Facet for bod]/ of, 

 lower dorsal vertebra. 



For transverse process of 

 lower dorsal vertebra. 



Vertebral extremity of a rib; external surface. (Gray.) 



Next externally is the flattened neck, about an inch long, 

 situated in front and above the transverse process of the lower 

 of the two vertebrae the head articulates with. It presents 

 an anterior and a posterior surface, a superior and an inferior 

 border. The anterior surface is flat and smooth, the posterior 

 rough for the attachment of the middle costotransverse liga- 

 ment. The superior border presents a rough ridge for the 

 attachment of the anterior costotransverse ligament. The 

 inferior border is rounded and free. On the lower part of the 

 posterior aspect of the junction of the neck and shaft is an 

 eminence, the tuberosity, most prominent in the upper ribs. 

 It is divided into two parts by an oblique groove. The inner 

 and lower part is articular for the transverse process of the 

 lower of the two vertebrae, with which the rib is connected; 

 the outer and upper part is rough for the posterior costo- 

 transverse ligament. 



The body is laterally compressed, presenting two flat sur- 



