THE CERVICAL VERTEBRA 



367 



distinguished from those of the back and loins by the following characters : 

 — 1st. The inferior spine of the body is strongly marked, and terminates 

 posteriorly in a tubercle (Fig. 12, j^). 2nd. The head of the body which 

 looks forward is very globular, and the corresponding cavity in the posterior 

 surface is of a cup-like shape (Fig. 1 2, i,), but larger than the head, in order 

 that it may receive the inter-articular cartilage which intei^venes. 3rd. The 

 spinous processes (Fig. 12, 3^ 4^ 5^ „) are very slightly marked. 4th. The 

 transverse processes (Fig. 12, b, b, b) wee unusually lengthened from before 

 backwards and downwards, and are each pierced with a hole for the passage 

 of the vertebral artery. 5 th. The four articular or oblique processes (Fig. 

 12, i5_ 15, 15) project greatly, and have an inclination from above downwards, 

 backwards and inwards. Each fossa for this purpose is large and deep. 



PECULIARITIES OF CERTAIN CERVICAL 

 VERTEBRAE 



The first cervical vertebra (counting from the head) has received the 

 name of atlas in human anatomy, from its surmounting all the others ; and 

 though in quadrupeds there is no longer the same reason for the appellation, 

 it has been extended to them. It deviates more completely than any of the 

 others from the type of all, the most remarkable differences consisting in 



Fig. 13.— Fore View ok the Atlas. 



1. Upper spine. 



2. 2. Wings or alse. 



3. Hole for the passage of the spinal cord. 



4. Lower spine. 



5. S ifaces for articulation with the condyles 



of the occiput. 

 C. Holes for the passage of the vertebral 



arteries. 



the almost total absence of body, and in the division of the large foramen 

 into two portions by a projecting ridge on the inner side of each lamina. 

 This ridge is not well shown in the fore view of this bone (Fig, 1 3), where 

 it is concealed by the articular surfaces, but it is easily seen in Fig. 14. 

 Below it the foramen is occupied by the tooth-like (odontoid) process of the 

 second cervical vertebra, which is confined in its place by a ligament stretched 

 across from one ridge to the other. Upon this, as on a pivot, the atlas 

 turns, carrying with it the head, and allowing of those lateral movements 

 which could not otherwise be accomplished. On each side of the spinal 

 foramen are the articular surfaces (Fig. 13, 5), which are covered with 

 cartilage, and form a firm hinge-like joint between the atlas and the occiput. 



