CERVICAL VERTEBRA. 145 



vertebrae are connected together by means of the articular processes and the inter- 

 vertebral cartilages ; while the transverse and spinous processes serve as levers 

 for the attachment of muscles which move the different parts of the spine. Lastly, 

 between each pair of vertebrae apertures exist through which the spinal nerves 

 pass from the cord. Each of these constituent parts must now be separately 

 examined. 



The Body or Centrum is the largest and most solid part of a vertebra. Above 

 and below it is flattened ; its upper and lower surfaces are rough for the attach- 

 ment of the intervertebral fibro-cartilages. and present a rim around their cir- 

 cumference. In front, it is convex from side to side, concave from above down- 

 ward. Behind, it is flat from above downward and slightly concave from side to 

 side. Its anterior surface is perforated by a few small apertures, for the passage 

 of nutrient vessels : whilst on the posterior surface is a single large, irregular 

 aperture, or occasionally more than one, for the exit of veins from the body of 

 the vertebra the ?vmp basis vertebrae. 



The Pedicles project backward, one on each side, from the upper part of the 

 body of the vertebra, at the line of junction of its posterior and lateral surfaces. 

 The concavities above and below the pedicles are the intervertebral notches ; they 

 are four in number, two on each side, the inferior ones being generally the deeper. 

 When the vertebra? are articulated the notches of each contiguous pair of bones 

 form the intervertebral foramina, which communicate with the spinal canal and 

 transmit the spinal nerves and blood-vessels. 



The Laminae are two broad plates of bone which complete the vertebral arch 

 behind, enclosing a foramen, the spinal foramen, which serves for the protection 

 of the spinal cord ; they are connected to the body by means of the pedicles. 

 Their upper and lower borders are rough, for the attachment of the ligamenta 

 tubflava. 



The Spinous Process projects backward from the junction of the two laminae, 

 and serves for the attachment of muscles. 



The Articular Processes, four in number, two on each side, spring from the 

 junction of the pedicles with the laminae. The two superior project upward, their 

 articular surfaces being directed more or less backward; the two inferior project 

 downward, their articular surfaces looking more or less forward. 1 



The Transverse Processes, two in number, project one at each side from the 

 point where the articular processes join the pedicle. They also serve for the 

 attachnien r of muscles. 



Character of the Cervical Vertebrae (Fig. 109). 



The Cervical Vertebrae are smaller than those in any other region of the spine, 

 and may readily be distinguished by the foramen in the transverse process, which 

 <lof> not exist in the transverse process of either the dorsal or lumbar vertebrae. 



The Body is small, comparatively dense, and broader from side to side than 

 frni before backward. The anterior and posterior surfaces are flattened and of 

 equal depth : the former is placed on a lower level than the latter, and its inferior 

 border is prolonged downward, so as to overlap the upper and fore part of the 

 vertebrae below. Its upper surface is concave transversely, and presents a pro- 

 jecting lip on each side : its lower surface is convex from side to side, concave 

 from before backward, and presents laterally a shallow concavity which receives 

 the corresponding projecting lip of the adjacent vertebra. The pedicles are 

 directed obliquely outward, and the superior intervertebral notches are deeper. 

 but narrower, than the inferior. The lamina 1 are narrow, long, thinner above than 

 below, and overlap each other, enclosing the spinal foramen, which is very large, 

 and of a triangular form. The spinous processes are short, and bifid at the 

 extremity to afford greater extent of surface for the attachment of muscles, the 

 two divisions being often of unequal size. They increase in length from the 



1 It may. perhaps, be as well to remind the reader that the direction of a surface is determined 

 by that of a line drawn at right angles to it. 

 10 



