THE SKELETON. 



second to the seventh inclusive are attached at the 

 junctions of the sternebrae. The eighth and ninth ribs 

 are attached near together on the caudal end of the 

 seventh sternebra. 



RIBS. 



There are thirteen pairs of ribs in the cat. The nine 

 cephalic are called true ribs because they articulate dor- 

 sally with the spinal column and ventrally with the 

 sternum. The other four (Fig. 28) are 

 false ribs, three of which articulate 

 ventrally with other ribs, while the 

 fourth has no ventral articulation, and 

 is therefore called a floating rib. Each 

 rib is composed of two parts, the ver- 

 tebral or bony portion and the sternal 

 or cartilaginous. 



The following description of the 

 sixth will serve to give a correct idea 

 in general of the anatomy of a rib. 

 Its vertebral portion (Fig. 29) presents 

 four features: a head or capitulum, 

 which articulates with the bodies of 

 the fifth and sixth thoracic vertebrae; 

 a tubercle, which articulates w r ith the 

 transverse process of the sixth thor- 

 acic vertebra ; a neck, which is the con- 

 stricted portion between the capitu- 

 lum and tubercle; and the shaft, in- 

 cluding the portion of the rib between 

 the tubercle and its articulation with 

 the sternal or cartilaginous portion. The bend in the shaft 

 beyond the tubercle is the angle. The sternal portion of 

 the rib, consisting of cartilage, is sometimes called the cos- 



6 



FIG. 29. CAUDAL AS- 

 PECT OF SIXTH RIB. 



ag, Angle; cr, pit for 

 articulation with 

 cartilaginous por- 

 tion; h, capitulum; 

 tik, neck; sh, shaft; 

 tb, tubercle with fa- 

 cet for articulation 

 with transverse pro- 

 cess. 



