22 DESCRIPTION OF THE SKELETON. 



THE SPINE. 



The head is set upon the atlas (Plate XXI. Figs. 3 and 4) by an articu- 

 lation, which has so great an obliquity that the atlas seems to give to it 

 very little mechanical support. This support depends almost wholly upon 

 the great strength of the muscles arising from the dorsal spines, and the 

 great power of the levers formed by the first six or seven dorsal vertebras. 

 cervical Cervical Vertebrae. General Description. — The vertebra? of the neck 



Vertebra. 



are seven in number. They extend obliquely from above downwards, and 

 from before backwards, so that the body of the seventh cervical is about 

 eleven inches lower than that of the first. The inferior face of these vertebras 

 is convex in a direction downwards and forwards, but flattened. There is 

 in the six superior a projecting ridge on the anterior part of the body, which 

 divides this face into two parts : this ridge is largest in the upper, and 

 diminishes in descending. The superior face of the whole cervical region, 

 considered generally, is very short, being about fourteen inches only in 

 length. Its anterior part is irregular, from the prominence of the spinous 

 processes of the first and second vertebras. The second spinous process, in 

 consequence of the bend of the neck, approaches nearly to the seventh ; the 

 four intervening being very small. The lateral portions of these vertebras 

 present as a whole an inferior ridge, formed by the projection of the trans- 

 verse processes, and a superior ridge constituted by the upper extremities 

 of the articulating processes. Between these two ridges is an excavation 

 for lodging the cervical muscles. 

 Atias. Particular Description. — The atlas (Plate XXI.) resembles the human 



as to its general form. The body presents inferiorly a very remarkable 

 projection at its middle for the common anterior vertebral ligament. The 



