CERVICAL VERTEBRAE. 143 



vertebra. On each side of it a small rough sinuosity may be 

 remarked, where the ligaments going to the sides of the tooth- 

 like process of the following vertebra are fastened ; and on each 

 side a small rough protuberance and a depression is observable, 

 where the transverse ligament, which secures the tooth-like 

 process in the sinuosity, is fixed, and hinders that process from 

 injuring the medulla spinalis in the flexions of the head. 



The atlas has as little spinous process as body; but, instead 

 of it, there is a large bony arch, that the muscles which pass 

 over this vertebra at that place might not be hurt in extending 

 the head. On the posterior and upper part of this arch, there 

 are two depressions, where the recti postici minores muscles take 

 their rise ; and at the lower part are two other sinuosities, into 

 which the ligaments that connect this bone to the following one 

 are fixed. 



The superior oblique processes, of the atlas are large, and 

 more horizontal than those of any other vertebra. They form 

 an oblong concave surface which has an internal aspect, and 

 corresponds exactly with the articulating surface on the external 

 side of each condyle of the os occipitis. Under the external 

 edge of the posterior part of each of these cavities is the fossa, 

 or deep open channel, in which the vertebral arteries make the 

 circular turn, as they are about to enter the great foramen of the 

 occipital bone, and where the tenth pair of nerves go out. In 

 some subjects, this fossa is covered with bone. The inferior 

 oblique processes, extending from within outwards and down- 

 wards, are large, circular, and slightly concave. So that this 

 vertebra, contrary to the other six, receives the bones with which 

 it is articulated, both above and below. \ 



The transverse processes of this vertebra are not much hol- 

 lowed or forked ; but are longer and larger than those of 

 any other vertebrae of the neck, for the origin and insertion 

 of several muscles ; and, therefore, those muscles which move 

 this vertebra on the second, have a considerable lever to act 

 with, because of the distance of their insertion from the axis of 

 revolution. 



The hole for the medulla spinalis is larger in the atlas than 



