166 



Joints of the Spine. 



Articulatio 

 atlantooccipitalis 



Capsula articularis 



Pars basilaris ossis occipitalis 

 Canalis hypoglossi 



Ligamentum alare 



Ligaraentum cruciatum atlantis 



N -<- Os occipitale 



<- Atlas 



Deepest layer of the 

 membrana tectoria 



Epistropbens 



Ligamentum transversum atlantis 



218. Occipital bone, first and seconcf 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; most of the membrana tectoria 



has been removed. The joint slits are partly opened.) 



Among its essential constituents Articulatio atlantoepistrophica (continued), 

 the lig amentum transversum atlantis (0. T. the transverse ligament) may first be men- 

 tioned. This tough, flat ligament (see also Figs. 217 and 221) goes behind the dens 

 epistrophei, has a broad origin from the medial surface of one massa lateralis atlantis 

 and is similarly fastened on the other side ; it is curved so as to be convex behind and 

 contains in the middle fibrocartilaginous deposits. On its anterior surface it is separated 

 by a small joint cavity from the odontoid process; on its posterior surface it is united 

 loosely with the membrana tectoria, From the middle of its upper margin a thinner 

 bundle of fibres runs vertically upward to the anterior circumference of the foramen 

 occipitale magnum and from the inferior margin one runs downward to the posterior 

 surface of the body of the second cervical vertebra. These fibre -bands together with 

 the ligamentum transversum atlantis make up the lig amentum cruciatum atlantis 

 (0. T. cruciform ligament). 



