146 THE SKELETON. 



fourth to the seventh. The articular processes are oblique : the superior are of 

 an oval form, flattened, and directed backward and upward ; the inferior forward 

 and downward. The transverse processes are short, directed downward, outward, 

 and forward, bifid at their extremity, and marked by a groove along their upper 

 surface, which runs downward and outward from the superior intervertebral 

 notch, and serves for the transmission of one of the cervical nerves. They are 

 situated in front of the articular processes and on the outer side of the pedicles. 

 The transverse processes are pierced at their base by a foramen, for the transmis- 

 sion of the vertebral artery, vein, and plexus of nerves. Each process is formed 

 by two roots : the anterior root, sometimes called the costal process, arises from 

 the side of the body, and is the homologue of the rib in the dorsal region of the 

 spine; the posterior root springs from the junction of the pedicle with the lamina, 

 and corresponds with the transverse process in the dorsal region. It is by the 



Anterior tubercle of trans-- 



verse process. | J ^ ET^^TV Transverse proem. 



Foramen for tvrteb 

 artery. 



Posterior tubercle of 

 transverse process. 



^-Superior artictdar 



process. 

 -Inferior articular process. 



?%* Spinal Forame 



y 



FIG. 109. Cervical vertebra. 



junction of the two that the foramen for the vertebral vessels is formed. The 

 extremity of each of these roots forms the anterior and posterior tubercles of the 

 transverse processes. 1 



The peculiar vertebrae in the cervical region are the first, or Atlas ; the second, 

 or Axis ; and the seventh, or Vertebra prominens. The great modifications in the 

 form of the atlas and axis are designed to admit of the nodding and rotatory 

 movements of the head. 



The Atlas (Fig. 110) is so named from supporting the globe of the head. The 

 chief peculiarities of this bone are that it has neither body nor spinous process. 

 The body is detached from the rest of the bone, and forms the odontoid process of 

 the second vertebra; while the parts corresponding to the pedicles join in front to 

 form the anterior arch. The atlas consists of an anterior arch, a posterior arch, 

 and two lateral masses. The anterior arch forms about one-fifth of the bone : its 

 anterior surface is convex, and presents about its centre a tubercle, for the attach- 

 ment of the Longus colli muscle ; posteriorly it is concave, and marked by a 

 smooth, oval or circular facet, for articulation with the odontoid process of the 

 axis. The upper and lower borders give attachment to the anterior occipito- 

 atlantal and the anterior atlanto-axial ligaments, which connect it with the occipital 

 bone above and the axis below. The posterior arch forms about two-fifths of the 

 circumference of the bone ; it terminates behind in a tubercle, which is the rudi- 

 ment of a spinous process, and g-ives origin to the Rectus capitis posticus minor. 

 The diminutive size of this process prevents any interference in the movements 

 between it and the cranium. The posterior part of the arch presents above and 

 behind a rounded edge for the attachment of the posterior occipito-atlantal liga- 



1 The anterior tubercle of the transverse process of the sixth cervical vertebra is of large size, 

 and is sometimes known as " Chassaignac's " or the "carotid tubercle." It is in close relation with 

 the carotid artery, which lies in front and a little external to il so that, as was first pointed out by 

 Chassaignac, the vessel can with ease be compiessed igainst it. 



