276 



HEAD AND NECK 



are attached to the dorsal surface of the transverse ligament. 

 The crus superius is the longer and flatter of the two, and 

 extends upwards on the posterior aspect of the dens to be 

 attached to the upper aspect of the basilar part of the 

 occipital bone, immediately beyond the anterior margin of 

 the foramen magnum. The crus inferiiis, much shorter, 

 extends downwards, and is fixed to the posterior aspect of 

 the body of the epistropheus. 



Membrana tectoria 

 Crus superius 



Apical 

 ligament 



*** 



Lateral 



mass of 



atlas 



Atlanto 

 pistropheal joint 



Body of epistro- 

 pheus 



Accessory atlan 



epistropheal 



ligament 



Crus inferius 



Membrana tectoria 



FlG. 104. Dissection showing the posterior aspects of the Ligaments con- 

 necting the Occipital Bone, the Atlas and the Epistropheus with each 

 other. 



Dissection. Detach the superior crus from the occipital 

 bone, and throw it downwards. The apical ligament is thus 

 displayed, and a better view of the alar ligaments is obtained. 



Ligamentum Apicis Dentis. The apical ligament of the 

 dens consists of two parts an anterior and a posterior. The 

 posterior part is a rounded cord-like ligament which is attached, 

 below, to the summit of the dens, and, above, to the anterior 

 margin of the foramen magnum. Inasmuch as it is developed 

 around the continuation of the notochord, from the dens 

 to the basis cranii, it is a structure of considerable morpho- 

 logical interest. The anterior part of the apical ligament is a 

 flat and weak band which is attached, above, to the anterior 



