OF THE ATLAS WITH THE OCCIPITAL BONE. 

 ARTICULATIONS OF THE SPINE WITH THE CRANIUM. 



229 



The ligaments connecting the spine with the cranium may be divided into two 

 sets those connecting the occipital bone with the atlas, and those connecting the 

 occipital bone with the axis. 



III. Articulation of the Atlas with the Occipital Bone. 



This articulation is a double condyloid joint. Its ligaments are the 



Anterior Occipito-atlantal. Two Lateral Occipito-atlantal. 



Posterior Occipito-atlantal. Two Capsular. 



The Anterior Occipito-atlantal Ligament (Fig. 153) is a broad membranous 

 layer, composed of densely woven fibres, which passes between the anterior 



J 



Arch for passage of 

 vertebral artery 

 and 1st cervical 



FIG. 154. Occipito-atlantal and atlanto-axial ligaments. Posterior view. 



margin of the foramen magnum above, and the whole length of the upper border 

 of the anterior arch of the atlas below. Laterally, it is continuous with the 

 capsular ligaments. In the middle line in front it is strengthened by a strong, 

 narrow, rounded cord, which is attached, above, to the basilar process of the 

 occiput, and, below, to the tubercle on the anterior arch of the atlas. This liga- 

 ment is in relation, in front, with the Recti antici minores ; behind, with the 

 odontoid ligaments. 



The Posterior Occipito-atlantal Ligament (Fig. 154) is a very broad but thin 

 membranous lamina intimately blended with the dura mater. It is connected, 

 above, to the posterior margin of the foramen magnum ; below, to the upper border 

 of the posterior arch of the atlas. This ligament is incomplete at each side, and 

 forms, with the superior intervertebral notch, an opening for the passage of the 

 vertebral artery and suboccipital nerve. The fibrous band which arches over the 

 artery and nerve sometimes becomes ossified. It is in relation, behind, with the 

 Recti postici minores and Obliqui superiores ; in front, with the dura mater of the 

 spinal canal, to which it is intimately adherent. 



The Lateral Ligaments are strong fibrous bands, directed obliquely upward and 



