THE HEAD AND NECK 



1303 



common ligament of the bodies of the vertebrae, and its central 

 portion is rendered thick by accessory fibres derived from the 

 anterior common hgament. 



The posterior atlanto-axlal ligament, also broad, thin, and mem- 

 branous, extends from the under aspect of the posterior arch of the 

 atlas to the upper borders and adjacent portions of the outer sur- 

 faces of the laminae of the axis. It is serially continuous with, 

 and represents, the hgamenta subflava of succeeding vertebrae. 



Atlanto-occipital Joints. — These are two in number, right and 

 left. They belong to the class diartlirosis and to the subdivision 

 eondylartlirosis. The articular surfaces are the condyles of the 

 occipital bone and the superior articular processes of the atlas. 



Posterior Occipito-axial Licameiit 

 (Membrana Tectoiia) 



Basilar Groove of Occipital Bone_ 



Lateral Odontoid or . ir- \ - 



Check Ligament 



; Superior Cms cf Cmdfonn 

 Ligament 



Occipito- 



atlancal 

 Capsule 



-- - Atlanto-axial 

 Joint 

 (opened) 



\ Inferior Cms of 

 Cmcif<»m Ligament 



Fig. 54: 



SfHDoas Process of Axis 



-Occipital. Atlantal, and Axial Ligaments (Posterior View). 



Ligaments. — These are as follows: the capsular ligaments and 

 the anterior and posterior occipito-atlantal hgaments, the latter 

 two being indirectly connected with the joints. 



The capsular ligaments are loose sacs which directly surroimd the 

 articulations. Their fibres are attached superiorly around the 

 margins of the occipital condyles, and inferiorly to the lateral 

 masses of the atlas, external to the circumference of the superior 

 articular processes. 



The anterior atlanto-occipital ligament, thin and membranous, 

 is attached inferiorly to the upper margin of the anterior arch of the 

 atlas, and superiorly to the under surface of the basilar process of 

 the occipital bone, close to the front part of the foramen magnum 



