CERVICAL VERTEBRA. 23 



-which extends from the head to the tail, and contains the spinai 

 cord, with its membranes and blood-vessels; the articular pro- 

 cesses strengthen the connections of the vertebrae, while the 

 spinous and transverse processes are levers to which muscles are 

 attached, their development having great influence on the physical 

 conformation and capabilities of the animal The ribs may be 

 regarded as continuations of the dorsal transverse processes ; they 

 form the inferior or hasmal arch of their own region. 



FALSE VERTEBR2E. 



The false vertehrce are found in the sacrum, which con- 

 sists of vertebral segments united by the ossification of their 

 connecting material, and in the coccyx, the skeleton of which 

 consists of rudimentary or imperfectly-developed vertebrae. The 

 sacral segments in the early stages of life are separable, and 

 they present all the characteristics of true vertebrae. 



CERVICAL VERTEBRiE. 



General Features. 

 (Fia. 8.) 



There are seven cervical vertehrce in all the Mammalia, with 

 the exception of the Three-toed Sloth, which has nine, and one of 

 the Sea-cows, which has six. They are numbered in order from 

 the head, the first receiving the special name of atla,8, and the 

 second that of axis or vertebra dentata ; these, with the sixth and 

 seventh, differ from the rest, which are essentially alike. 



The centra or bodies of the cervical vertebrae are larger and 

 longer than those of any other true vertebrae, and frequently 

 measure upwards of four inches in length ; they are quadrangular 

 in shape, their anterior extremity or head being convex and some- 

 what heart-shaped, with the apex downwards, while the posterior 

 extremity presents a corresponding cup-hke cavity. The flexi- 

 bility of the neck is partly due to these convexities and cavities, 

 which are more pronounced in the cervical region than in other 

 parts of the column. The superior surface is flattened, and pre- 

 sents, close to the pedicle on each side, a distinct furrow, which 

 contains the spinal vein ; these lateral furrows are united by 



