168 



Joints of the Spine. 



Pars basilaris ossis occipitalis 



Canalis hypoglossi 



^Membrana tectoria 



Atlas --->- 



Processus trans- 

 versus atlautis 



Capsulae articulares <' 



F|>islropli-ns 



Ligamentum longitudinale posterius 



220. Occipital bone and first three cervical 

 vertebrae with ligaments, from behind. 



(The part of the occipital bone situated behind the middle of the foramen occipitale magnum 

 and the arches of the cervical vertebrae have been removed; the most superficial, thin layer 

 of the ligamentum longitudinale posterius has also been removed. The right joint slits are opened.) 



The articulatio atlantoepistrophica is covered behind by the membrana 

 tectoria (0. T. occipito-axial ligament) (see also Fig. 221). This lies as a broad, 

 quadrangular fibrous plate behind the ligamentum cruciatum atlantis, is loosely connected 

 with it and is separated from the dura mater of the canalis vertebralis by a very thin 

 fibrous layer which is considered as a continuation of the superficial long bands of the 

 ligamentum longitudinale posterius, while the membrana tectoria itself is looked upon as 

 the especially strongly developed uppermost part of the deep, short -fibred layer of the 

 ligamentum longitudinale posterius (see p. 161). The membrana tectoria arises from 

 the posterior surface of the clivus as well as from the anterior and lateral circumference 

 of the foramen occipitale magnum where it is broadest; its fibres converge downward 

 and become fastened in several strands to the posterior surface of the body of the epi- 

 stropheus. Short bands of fibres between the atlas and the epistropheus are attached 

 in the depth, lateralward, to the membrana tectoria (see Fig. 2 1 8). 



