46 



MAMMALIAN ANATOMY 



The Lumbar : Vertebrae, the following seven at the dorsal part of 

 the abdominal cavity in the region of the loins ; 



The Sacral 2 Vertebras, the following three, which are firmly united 

 and form the sacrum, whereto the hip-bones of the hind legs are 

 attached ; 



The Caudal :! Vertebras, the remaining eighteen to twenty-three, 



form the tail. 



FIG. 15. 



VERTEBRAL COLUMN. 



Lumbar 



Sacral. 



STERNUM. 



THE AXIAL SKELETON. (Greatly reduced.) 



The Sacral Vertebrae are sometimes called the immovable or false 

 vertebrae, as distinguished from the others, the true vertebrae. 



CHARACTERS COMMON TO ALL VERTEBRA. 



General Description. Each vertebra, whatever its shape, con- 

 sists of two essential parts (Fig. 16), the ventral cylindrical body or 

 centrum, 4 and the dorsal transverse neural ' arch. The space between 

 the arch and the body is the neural canal. The ends of the body are 

 smooth, and bound to the ends of adjoining vertebras by means of 

 intervening plates of cartilage. The arch is formed of pedicles G and 

 laminae. 7 



The pedicles are the upright ventral parts of the sides of the arch. 

 The lamina slope dorsally and toward each other from the dorsal ends 

 of the pedicles, and, meeting in the middle line, form the horizontal 

 roof of the neural canal ; at their point of meeting the vertebra is 

 prolonged dorsally into the neural spine or spinous process. 



1 From lumbus, a loin. J From sacer, sacred. 



3 From cauda, the tail. * Centrum, centre. 



5 From neuron (G-r.), a nerve. 6 From pediculum, a little foot. 



7 Lamina, a thin sheet. 



