24 



ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. 



Fig. 4. — The cervical vertebra seen from behind and partly from the side (f). 

 Fig. 5. — The fifth cervical vertebra seen from above ( T ). 

 Fig. 6. — The seventh cervical vertebra seen from above ( T ). 

 Fig. 7. — The atlas seen from above ( T ). 

 Fig. 8. — The axis seen from above ( T ). 



bodies are relatively small, low, oblong (or quadrilateral with rounded corners), and they in- 

 crease in size from above downward. The bodies are smaller than in any other region of the 

 spine, and their upper surfaces are concave from side to side and slightly convex from before 

 backward, while the lower surfaces are concave from before backward and slightly convex from 

 side to side. As a consequence of this, the upper surface of every vertebra projects laterally 



beyond the body of the vertebra next above 

 (Figs. 3 and 4). 



The arches of the cervical vertebras (Fig. 5) 

 are of medium height and arise by a pedicle which 

 is directed outward and backward. Together with 

 the body, the arch surrounds a spinal foramen 

 which is very wide, especially in its transverse 

 diameter. The articular processes (with the ex- 

 ception of those of the upper two vertebras) are 

 placed obliquely, so that the plane of the articu- 

 lation passes from above downward and from 

 before backward, and the articular surfaces are 

 consequently in a middle position between a hori- 

 zontal and a frontal plane, those nearer the skull 

 approaching the horizontal position, and those 

 nearer the thoraa'c vertebrae the frontal plane. 

 The transverse processes (Figs. 5 and 6) of 

 all the cervical vertebrae are perforated by a large round foramen (foramen transversarium), 

 a peculiarity which distinguishes the cervical from all other vertebrae. Furthermore, the ends 

 of the transverse processes are prolonged into two tubercles separated by a groove (sulcus nervi 

 spinalis) (Fig. 5), situated upon the surface of the transverse process. 



The anterior root of the transverse process, which passes directly outward from the body of the vertebra and is 

 separated from the posterior root by the foramen transversarium, the sulcus nervi spinalis, and the constriction between 

 the two tubercles, is known as the costal process (processus coslurius), and represents a rudimentary rib adherent to the 

 true transverse process which is represented by the posterior root. This costal process is occasionally independent, 

 especially in the seventh 1 en i< al vertebra, and forms then a cervical rib. 



The spinous processes (Figs. 4 and 5) are for the most part small, somewhat downwardly 

 inclined, and distinctly bifid at their apices. 



From the third to the sixth the cervical vertebrae are typical. The seventh (Fig. 6) is dis- 

 tinguished by possessing a long spinous process which is not bifid and is directed downward, 



Fig. 3. — Cervical vertebra- seen from in front. 



