LIGAMENTS OF THE VERTEBRAL COLUMN. 123 



The movements taking place between the cranium and atlas, are 

 those of flexion and erection, giving rise to the forward nodding of the 

 head. When this motion is increased to any extent the whole of the 

 cervical region concurs in its production. 



3. Articulation of the Axis with the Occipital bone. The ligaments 

 of this articulation are three in number, 



Occipito-axoid, 

 Two odontoid. 



The occipito-axoid ligament (apparatus ligamentosus colli) is a broad 

 band, which covers in the odontoid process and its ligaments. It is 

 attached below to the body of the axis, where it is continuous with 

 the posterior common ligament ; superiorly it is inserted by a broad 



Fig. 55.* 



expansion, into the basilar groove of the occipital bone. It is firmly 

 connected opposite the body of the axis, with the dura mater ; and 

 sometimes is described as consisting of a central and two lateral por- 

 tions ; this however is an unnecessary refinement. 



The odontoid ligaments (alar) are two short and thick fasciculi of 

 fibres, which pass outwards from the apex of the odontoid process, to 

 the sides of the occipital foramen and condyles. A third and smaller 

 fasciculus (ligamentum suspensorium ) proceeds from the apex of the 

 odontoid process to the anterior margin of the foramen magnum. 



These ligaments serve to limit the extent to which rotation of the 

 head may be carried, hence they are termed check ligaments. 



* The upper part of the vertebral canal, opened from behind in order to shew 

 the occipito-axoid ligament. 1. The basilar portion of the sphenoid bone. 

 2. Section of the occipital bone. 3. The atlas, its posterior arch removed. 

 4. The axis, the posterior arch also removed. 5. The occipito-axoid ligament, 

 rendered prominent at its middle by the projection of the odontoid process. 

 6. Lateral and capsular ligament of the occipito-atloid articulation. 7. Cap- 

 sular ligament between the articulating processes of the atlas and axis. 



