20 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM 



above down. The posterior surface is slightly concave from 

 side to side, and marked by one or two venous foramina. The 

 neural arch consists of two symmetrical portions meeting in 

 the median plane behind. The anterior part or pedicle rises 

 from a point on the body where the lateral and posterior sur- 

 faces meet; the posterior part or lamina is broad and flat. 

 The upper and lower borders of pedicles form vertebral notches, 

 becoming intervertebral foramina between contiguous vertebra. 

 The spinous process projects back from the junction of the 

 two lamina?. The transverse processes, one on either side, pro- 

 ject outward from the arch at the junction of the pedicle 

 with the lamina. The articular processes, two superior and 

 two inferior, project upward and downward at the point of 

 origin of the transverse processes. 



The foramen is bounded anteriorly by the body, posteriorly 

 and laterally by the arch; the series of rings thus formed con- 

 stitutes the spinal canal. 



The Cervical Vertebrae 



The body is smaller than those of any other region; it is 

 broad transversely; the upper surface is concave because of 

 the upward projection of lateral lips, and is sloped down in 

 the front. The under surface is rounded at the sides and lipped 

 anteriorly, so there is interlocking at the sides to prevent 

 lateral displacement an anterior lip to prevent posterior, 

 and articular processes to prevent anterior, dislocations. The 

 lamina? are long and flat, overlapping those of the vertebra 

 next below. The superior and inferior notches are nearly equal 

 in depth. The spinous processes are short and bifid, increasing in 

 length from the fourth to the seventh inclusive. The transverse 

 processes are directed outward, downward, and forward, and 

 present at their extremities an anterior and a posterior tubercle. 

 Each process is grooved above, and perforated vertically at 

 its base by the vcrtebrarterial foramen for a vein, artery, and 

 plexus of nerves. This foramen is between the two roots of 

 the process, the posterior corresponding to a dorsal transverse 

 process, and the anterior to a rib. It is characteristic of this 

 region. The articular processes are placed at the extremities 

 of a short vortical column of bone; the superior articular sur- 

 face is oval and looks up and back; the inferior down and 



