116 MAMMALIAN ANATOMY 



cervical and lumbar regions, but a small diameter in those thoracic 

 vertebrae which have transverse processes. 



(3) The intervertebral foramina are largest in the last cervical, 

 the cephalic thoracic, and the last lumbar vertebrae, and smallest in 

 the mid-thoracic region. 



(4) The transverse processes spring from the sides of the bodies 

 in the cervical, the lumbar, the sacral, and the caudal vertebrae, and 

 from the pedicles in the thoracic vertebrae. In the cervical region 

 we observe the two parts of the transverse process, the dorsal trans- 

 verse element and the ventral costal element, coalesced distal to the 

 arterial canal. In the thoracic region the ventral costal element is 

 replaced by the rib, and in the terminal thoracic and the lumbar 

 region the dorsal element becomes the elongated ridge, whereof the 

 cephalic end is the mammillary process and the caudal end the ac- 

 cessory process, while the ventral element is known as the transverse 

 process. In the first and second sacral vertebrae a costal element is 

 developed in the transverse process or lateral mass, and supports the 

 articulation with the innominate. 



In the four regions, therefore, the dorsal element is represented by 



1. The transverse element of the transverse process, 



2. The transverse process, 



3. The mammillary and accessory processes, 



4. The transverse element in the lateral mass. 

 The ventral element is represented by 



1. The costal element of the transverse process, 



2. The rib, 



3. The transverse process, 



4. The costal element in the lateral mass. 



The cephalo-caudal diameter of the transverse process is relatively 

 great in all the cervical vertebrae except the second and seventh, and 

 also in the ninth and tenth thoracic, the sacral, and those vertebrae 

 of the tail which present both cephalic and caudal transverse pro- 

 cesses. In the cervical region the process is directed laterally toward 

 the tail and ventrally ; in the thoracic, laterally ; in the lumbar, 

 laterally toward the head and ventrally ; in the sacral, laterally ; in 

 the caudal, laterally and toward the tail. 



(5) The bodies are flattened dorso-ventrally in the cervical, 

 cephalic thoracic, sacral, and cephalic caudal regions, and are rela- 



