LIGAMENTS OF THE VERTEBRAL COLUMN. 141 



ligaments form a strong sheath around the vessels and nerves which pass 

 through the carotid and jugular foramina. 



The capsular ligaments are the thin and loose ligamentous capsules 

 which surround the synovial membranes of the articulations between the 

 rondyles 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 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 lone. The ligaments of 

 this articulation are three in number, 



Occipito-axoid, TW T O 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 continu- 

 ous with the posterior common ligament ; 

 superiorly it is inserted by a broad ex- 

 pansion, 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 

 portions ; 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 

 (hgamentum suspensorium), or middle straight ligament, 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. 



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

 culation are^ve in number, 



Anterior atlo-axoid, Two capsular, 



Posterior atlo-axoid, Transverse. 



The anterior ligament consists of ligamentous fibres, which pass from 

 the anterior tubercle and arch of the atlas to the base of the odontoid pro- 

 cess and body of the axis, where they are continuous with the commence- 

 ment of the anterior common ligament. 



* 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 tho 

 occipital bone. 3. The atlas, its posterior arch removed. -I. The axis, the posterior 

 arch also removed. 5. The occipito-axoid ligament, rendered prominent at its mi Mis 

 by the projection of the odontoid process. 6. Lateral and capsular ligament of the oe- 

 cipito-atioid articulation. 7. Capsular ligament between the articulating processes o" 

 the atlas and axis. 



