272 HEAD AND NECK 



tissue, which allows the egress from the vertebral canal of 

 some small veins. The width of the ligaments in the different 

 regions of the vertebral column depends upon the size of 

 the vertebral canal. Therefore, they are widest in the neck 

 and in the lumbar part of the column. The ligamenta flava, 

 by virtue of their great strength and elasticity, are powerful 

 agents in maintaining the curvatures of the vertebral column ; 

 they also give valuable aid to the muscles in restoring the 

 vertebral column to its original position after it has been bent 

 in a ventral direction. 



The inter spinous ligaments are most strongly developed in 

 the lumbar region, where they fill up the intervals between 

 the adjacent margins of contiguous spinous processes. In 

 the thoracic region, and more so in the neck, they are very 

 weak. 



The supraspinous ligaments are thickened bands which 

 connect the summits of the spinous processes. In the neck 

 they are replaced by the ligamentum nuchse (p. 67). 



The inter transverse ligaments are feebly marked in the 

 cervical region and extend chiefly between the anterior bars 

 of the transverse processes. 



Articulations of the Epistropheus, Atlas, and Occipital 

 Bone. The articulations which exist between the atlas and 

 the occipital bone and the atlas and the epistropheus all 

 belong to the diarthrodial -class. Between the atlas and 

 epistropheus (O.T. axis) there are three such joints viz., 

 a pair between the opposed articular processes, and a third 

 between the anterior face of the dens and the posterior face 

 of the anterior arch of the atlas. Between the atlas and 

 occipital bone there is a pair of joints viz., between the 

 occipital condyles and the elliptical cavities upon the 

 upper aspects of the lateral masses of the atlas. In ad- 

 dition, the epistropheus is attached to the occipital bone by 

 ligaments. 



The ligaments connecting the three bones together may 

 be divided into three main groups, as follows : 



Ligaments connecting atlas^ 

 with epistropheus, . . 



Anterior longitudinal. 



Ligamenta flava. 



Capsular. 



Transverse . portion of cruciate ligament 



with inferior crus. 

 Accessory ligaments of the atlanto-epi- 



stropheal joints. 



