82. SKELETON. 



cesses a rounded tubercle is found on either side of the bone. 

 The transverse ligament of the neck is extended between the 

 two tubercles, and keeps the processus dentatus in its place. 



The short thin bridge at the fore part of the bone, is marked 

 in front by a tubercle, and behind by an articular face which 

 touches the processus dentatus. The bridge or section of the 

 ring forming the posterior part of the bone, is much longer and 

 more arched than the anterior. It also has in its centre a tu- 

 bercle, occupying the position of a spinous process. At the 

 anterior extremity of this bridge, just behind the upper oblique 

 process, there is a groove, and sometimes a canal, made by the 

 vertebral vessels, just before they enter the foramen magnum 

 oecipitis. 



The transverse processes of this vertebra are at the sides of 

 the thick part of the ring. From their greater length, they pro- 

 ject considerably beyond the transverse processes below, and 

 are also perforated at their bases by the vertebral vessels, which 

 have a very winding course from them into the cranium. 



The spinal canal of the first vertebra, excluding the space for 

 the processus dentatus and transverse ligament, is the largest in 

 the spine: by which ample provision is made against injuries of 

 the medulla spinalis, notwithstanding the great latitude of the 

 rotation of this bone upon the second vertebra. A considera- 

 ble vacuity is left between the upper posterior margin of the 

 atlas and the contiguous surface of the os oecipitis, for the gin- 

 glymoid motion of the head upon the atlas, 



The second vertebra of the neck is particularly remarkable 

 for the elongation of its body above into the processus dentatus 

 or tooth-like process. This process rises as high as the superior 

 margin of the atlas, and almost touches the anterior margin of 

 the foramen magnum oecipitis.* It presents an articular face 

 in front, where it touches the first vertebra. It presents also a 

 smooth face behind, W 7 here it touches the transverse ligament 

 Above the latter face, on each side, is a flat surface for the ori- 

 gin of the moderator ligaments, and the very point above pre- 

 sents a small rough surface for the vertical ligament going to 

 the margin of the foramen magnum. 



* Sometimes it even forms a joint with it t 



