164 



Joints of the Spine. 



Membrana atlantooccipitalis anterior x 



Os occipitale >- 



Capsula articularis - 

 Atlas --->(. 



Capsula articularis - 



Epistrophens -->- 



Joint cavity between corpus 

 vertebrae and fibrocartilago 

 intervertebralis (see p. 156) 



Fibrocartilago intervertebralis 



Tuberculum pharyngeum 



Pars basilaris ossis occipitalis 



j^M Canalis hypoglossi 



Articulatio atlantooccipitalis 



Processus transversus 

 atlantis 



Articulatio atlantoepistrophica 



Processus transversus 

 epistrophei 



Procesaus transversus 

 vertebrae cervicalis III 



Ligamentum longitudinale anterius 



215- Occipital bone and first three cervical 

 vertebrae with ligaments, from in front. 



(The joints have been partially opened.) 



The articulatio atlantooccipitalis (occipital joint, 0. T. articulation of the atlas 

 with the occipital bone) (see also Figs. 216 and 219) is formed so that the condyli occipitales 

 move in the foveae articulares superiores atlantis. Between the borders of these cartilaginous 

 joint surfaces are stretched the loose capsulae articulares (0. T. capsular ligaments). The 

 interspaces between the arches of the atlas and the occipital bone are filled up by the mem- 

 branae atlantooccipitales. 



The membrana atlantooccipitalis anterior (0. T. anterior occipitoatlantal ligaments) 

 extends as a flat, tough band^between the pars basilaris ossis occipitalis and the arcus anterior 

 atlantis ; its fibres run essentially vertically. In the middle it is fused with the uppermost part 

 of the ligamentum longitudinale anterius, at the borders with the capsulae articulares. 



The membrana atlantooccipitalis posterior (0. T. posterior occipitoatlantal ligament) (see 

 Figs. 216 and 221) goes from the posterior circumference of the foramen occipitale magnum 

 to the arcus posterior atlantis. Its lower, medial part is extraordinarily thin and firmly fused 

 with the dura mater. Its upper lateral part consists of stronger fibrous bands; they extend 

 obliquely lateralward and are fastened there to a fibrous arch, sometimes ossified, which 

 bridges over the sulcus a. vertebralis and transforms it into a canal, through which pass the 

 a. and v. vertebralis and the n. cervicalis I. 



The articulatio atlantoepistrophica (joint for rotation of head, 0. T. articulation 

 of the atlas with the axis) (see also Figs. 217 221) is formed in that the facies articulares 

 inferiores atlantis move upon the facies articulares superiores epistrophei and that, at the same 

 tune, the dens epistrophei turns with its two facies articulares, in the cylindrical space which 

 is bounded in front by the arcus anterior atlantis, behind by the ligamentum transversum 

 atlantis. Between the border of each inferior joint-surface of the atlas and the upper joint-surface 

 of the epistropheus are stretched loose capsulae articulares (0. T. capsular ligaments); there' 

 is also a similar joint-capsule between the border of the fovea dentis of the atlas and the facies 

 articularis anterior epistrophei, as well as between the circumference of the facies articularis 

 posterior epistrophei and the anterior surface of the ligamentum transversum atlantis. 



