5° ELEMENTS OF MAMMALIAN ANATOMY. 
to the seventh inclusive are attached at the junctions of the 
sternebree. 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. 28) are false 
ribs, three of which articulate ventrally 
with other ribs, while the fourth has 
no ventral articulation, and is there- 
fore called a floating rib. Each rib 
is composed of two parts, the vertebral 
or bony portion and the sternal or car- 
tilaginous portion. 
The following description of the 
sixth will serve to give a correct idea 
in general of the anatomy ofa rib. Its 
vertebral portion (Fig. 29) presents 
four features: a head or capitulum, 
Fic. 29. Caunar As- which articulates with the bodies of 
PECT OF SIXTH RB. the fifth and sixth thoracic vertebra; a 
ag, Angle; cr, pit for 
articulation with fubercle, which articulates with the 
cartilaginous por- - _— So : 
tion: ft. capitulum; tTamsverse process of the sixth thoracic 
nk, neck; sh, shaft; vertebra; a neck, which is the con- 
tb, tubercle with ieched +s bene 1 . 
facet for articula- Stricted portion etween the capitulum 
tion with transverse and tubercle; and the shaft, including 
process. a : 2 5 
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 carti- 
lage, is sometimes called the costal rib. In the sixth rib the 
costal portion is about half as long as the vertebral portion. 
