108 



LIGAMENTS OF THE VERTEBRAL COLUMN. 



Fig. 44* 



attached below, to the base of the transverse process of the atlas at 

 each side, and above to the transverse process of the occipital bone. 

 With a ligamentous expansion derived from the vaginal process of 

 the temporal bone, these ligaments form a strong sheath around the 

 vessels and nerves which pass through the carotid and jugular fora- 

 men. 



The capsular ligaments are the thin and loose ligamentous cap- 

 sules, which surround the synovial membranes of the articulations, 

 between the condyles of the occipital bone and the superior articular 

 processes of the atlas. The ligamentous fibres are most numerous 

 upon the anterior and external part of the articulation. 



The movements taking place between the cranium and atlas, are 

 those of flexion and extension, 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 (appa- 

 ratus ligamentosus colli) is a broad 

 band, which covers in the odontoid 

 process and its ligaments. It is at- 

 tached below to the body of the axis, 

 and is continuous with the posterior 

 common ligament ; superiorly it is 

 inserted by a broad expansion, into 

 the basilar groove of the occipital 

 bone. It is firmly connected oppo- 

 site the body of the axis, with the 

 dura mater. It is sometimes de- 

 scribed as consisting of a central and two lateral portions; this how- 

 ever 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 also proceeds from the apex of the odontoid pro- 

 cess, to the anterior margin of the foramen magnum.f 



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

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



4. Articulation of the Atlas with the Axis. The ligaments of this 

 articulation are jive in number: 



* The upper part of the vertebral canal, opened from behind in order to show 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 oc- 

 cipito-atloid articulation. 7. Capsular ligament between the articulating process of the 

 atlas and axis. 



t Called middle straight ligament. G. 



