THE SKELETON 6 I 



bone, the coccyx, while in the embryo eight segments make up 

 the caudal region. Ossification takes place, however, in only 

 five or six segments. 



THE STERNUM 



The sternum of the cat is composed of eight pieces, called 

 steniebrcB, which lie in the median line on the ventral side of 

 the chest (Fig. 22). The sternum serves for the attachment 

 of the cartilaginous portions of nine pairs of ribs. The first 

 sternebra (Fig. 29), which ends craniad in a laterally com- 

 pressed pointed process is the manubrium. The six succeed- 

 ing sternebrae form the body or corpus sterni ; the caudal piece 

 is called the xiphoid process. It is terminated by a flat piece 

 of cartilage. The cartilaginous portion of the first rib articu- 

 lates with manubrium near its middle. The ribs from the 

 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 cranial 

 are called true ribs because they articulate dorsally with the 

 spinal column and ventrally with the sternum. The other 

 four (Fig. 29) 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 vertebral or bony portion and the sternal or cartilagi- 

 nous portion. 



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. 30) presents four features: a head or capitidum, 

 which articulates with the bodies of the fifth and sixth thoracic 

 vertebrae; a tubercle, which articulates with the transverse proc- 

 ess of the sixth thoracic vertebra; a neck, which is the con- 



