CERVICAL VERTEBRA 44 T 



The oblique articular processes are oval, the two superior 

 being directed upward and backward, and the two inferior 

 downward and forward ; the surfaces of the superior are 

 rather convex, those of the inferior concave. 



CERVICAL VERTEBRA INDIVIDUAL CHARACTERISTICS. 



The atlas , or first cervical vertebra, so called from sup- 

 porting the head, differs from the rest in having no body 

 nor spinous process, and consisting simply of a bony ring. 

 A tubercle marks this ring on its anterior portion ; behind, 

 on the same part, the A FIG. 125. B 



surface is concave, 

 smooth, and oval, for 

 articulating with the 

 tooth-like process of 

 the axis or second 

 vertebra. The upper and lower edges of this ring are for 

 the attachment of ligaments. The posterior arch is long, 

 slender, and presents a tubercle instead of a spine, upon 

 the upper surface of which, near the oblique processes, is a 

 groove for the vertebral artery, in making its curve, to 

 enter the brain. It also receives the sub-occipital or first 

 cervical nerve. The spinal foramen is very large, and 

 divided by the transverse ligament into two ; the anterior 

 and smaller receives the odontoid process, the posterior and 

 larger contains the spinal cord. The intervertebral notches 

 are behind instead of being in front of the oblique processes, 

 as in all the other vertebras. The superior oblique pro- 

 cesses are horizontal, concave, and their smooth surfaces 

 look from before, backward and outward ; they articu- 

 late with the condyles of the occipital bone, and are admi- 

 rably adapted to the nodding motion of the head. The 



FIG. 125, A represents the upper surface of the Atlas. 1 Tubercle in place 

 of spinous process. 2 Posterior part of ring of atlas. 3 Where the transverse 

 ligament is attached. 4 Superior articular process. 5 Groove leading to 

 vertebral foramen. 6 Transverse process. 7 Articular surface for odontoid 

 process. 8 Anterior margin of ring of atlas. 9 Foramen for spinal marrow. 



FIG. 125, B represents the lower surface of Atlas. 1 Tubercle in place of 

 spinous process. 23456789 Correspond to similar points, as in Fig. 125, A. 



