38 



THE SKELETON. 



is the strong, prominent process, tooth-like in form (hence the name odontoid), 

 which rises perpendicularly from the upper surface of the body. The body is 

 deeper in front than behind, and prolonged downward anteriorly so as to overlap 

 the upper and fore part of the next vertebra. It presents in front a median 



Odontoid process. 



Bough surface for check ligaments.' 

 Articular surf ace for transverse ligament.. 



Articular surface for 

 atlas. 



Anterior root. 



Body. 



IKf ^"^^W *%f fqjy jf 



Spinous process.^ 



f I mmw -^^ 



I Transverse process. 

 Inferior articular process. 

 FIG. 3. Second cervical vertebra, or axis. 



longitudinal ridge, separating two lateral depressions for the attachment of the 

 Longus colli muscle of either side. The odontoid process presents two articulating 

 surfaces: one in front, of an oval form, for articulation with the atlas; another 

 behind, for the transverse ligament the latter frequently encroaching on the 

 sides of the process. The apex is pointed, and gives attachment to the middle 

 fasciculus of the odontoid or check ligaments (ligamentum suspensoriuni). Below 

 the apex the process is somewhat enlarged, and presents on either side a rough 

 impression for the attachment of the lateral fasciculi of the odontoid or check 

 ligaments, which connect it to the occipital bone ; the base of the process, where 

 it is attached to the body, is constricted, so as to prevent displacement from the 



transverse ligament, which binds 



Bod y- it in this situation to the anterior 



arch of the atlas. Sometimes, 

 however, this process does become 

 displaced, especially in children, 

 in whom the ligaments are more 

 relaxed : instant death is the re- 

 sult of this accident. The in- 

 ternal structure of the odontoid 

 process is more compact than that 

 of the body. The pedicles are 

 broad and strong, especially their 

 anterior extremities, which coa- 

 lesce with the sides of the body 

 and the root of the odontoid 

 process. The laminae are thick 

 and strong, and the spinal fora- 

 men large, but smaller than that 

 of the atlas. The transverse proc- 

 esses are very small, not bifid, 

 and perforated by the foramen 

 for the vertebral artery, which is 

 directed obliquely upward and outward. The superior articular surfaces are round, 

 slightly convex, directed upward and outward, and are peculiar in being supported 

 on the body, pedicles, and transverse processes. The inferior articular surfaces 

 have the same direction as those of the other cervical vertebra. The superior 



Spinons process. 

 PIG. 4. Seventh cervical vertebra, or vertebra prominens. 



