274 SKELETON OF THE RABBIT 



a. A typical rib, such as the fifth, consists of two 



portions of very unequal size, joined together 



almost at right angles. 



i. The vertebral portioD, which is the larger part 

 of the rib, is a flattened rod of bone, strongly 

 curved above, nearly straight below. The 

 dorsal end or capitulum articulates with a 

 concave surface, furnished partly by the cen- 

 trum of the corresponding vertebra, and partly 

 by that of the vertebra next in front. A short 

 way beyond the capitulum, and on the dorsal 

 surface of the rib, is the tubercle or surface 

 for articulation with the transverse process 

 of the correspondiag vertebra ; and imme- 

 diately beyond the tubercle is a short vertical 

 projection for the attachment of ligaments, 

 ii. The sternal portion is a short bar of calcified or 

 imperfectly ossified cartUage, connecting the 

 lower end of the vertebral portion with the 

 sternum. 



b. The ribs in general. The ribs increase in length 



from the first, which is very short, to the sixth, 

 behind which they diminish. The first nine pairs 

 of ribs have both capitular and tubercular articu- 

 lations with the vertebrae : in the remaining three 

 (or four) pairs, which are more slender than the 

 anterior ones, the tubercles are absent, and the 

 capitular articulations, which alone are present, 

 are confined to the corresponding vertebrte. 



The sternal portions of the first seven pairs 

 articulate directly with the sternum : the remain- 

 ing ones do not reach the sternum, though those 

 of the eighth and ninth pairs are closely connected 

 with the ribs in front of them. 



2. The sternum is an elongated, laterally compressed 

 median rod, situated in the ventral waU of the thorax, 

 and divided transversely into segments or stemebrse^ 



