Bones of the Skull. 



Sulcus sagittalis 



Margo lambdoideus 



Protuberantia occipitalis 

 interim 



Fossa occipitalis superior 

 Sulcus transversus 



Squama 

 occipitalis 



Fossa occipitalis 

 inferior 



Processus jugularis 



Sulcus transversus 

 Canalis condyloideus 

 Incisura jugularis 

 \ ' Probe in canalis hypoglossi 



Processus intrajugularis 

 \ Tuberculum jugulare 



Sulcus petrosus inferior 

 Clivus 



Pars basilaris 



1. Occipital bone, OS OCCipitale, viewed from in front. 



The impaired os occipitale (occipital bone) (see also Figs. 2, 3, 55, 56 and 59 66) 

 forms the posterior inferior part of the skull. It is divisible into four parts ; an unpaired 

 basilar part (pars basilaris); an unpaired squamo- occipital part (squama occipitalis) and the 

 paired lateral parts (paries later ales). These parts are so arranged around the large occipital 

 foramen (foramen occipitale magnum) that the pars basilaris lies in front of the foramen, 

 the squama occipitalis behind and above it, while the partes laterales lie lateral from it. 

 Through the great occipital foramen pass the meningeal rami of the vertebral arteries, the 

 vertebral arteries themselves, the anterior and posterior spinal arteries, the basilar plexus, the 

 nn. accessorii, the roots of the nn. cervicales I, and the medulla oblongata. 



The pars basilaris (see also Figs. 2, 3, 59, 60 and 63 66) presents, up to about the 

 twentieth year of life, a rough surface in front corresponding to its attachment to the body of the 

 sphenoid bone ; the union is effected by a layer of hyaline cartilage which ossifies later (fissura and 

 synchondrosis sphenooccipitalis). The two lateral, slightly jagged edges lie upon the posterior 

 angle of the petrous portion of the temporal bone (fissura and synchondrosis pelrooccipitalis); 

 on the upper surface is situated the groove, formed by the two bones in common, corresponding 

 to the sulcus petrosus inferior (fur the sinus petros. inf.). The posterior border, sharp in the 

 middle, is smooth and concave, and forms the anterior circumference of the for. occip. mag. The 

 superior surface is smooth and slightly concave in a frontal direction ; it helps to form the clivus 

 inasmuch as it is directly continuous with the posterior surface of the dorsum sellae of the 

 sphenoid. The clivus gives support to the pons, the vertebral arteries, the basilar artery and their 

 branches. The inferior surface presents in the median line a small projection, the pharyngeal tubercle 

 (tuberculum pharyngeum) (for the attachment of the lig. longitud. ant. and the m. constrictor 

 pharyngis sup.), and also alternating ledges for the m. rectus capitis ant. and the m. longus capitis. 

 Spalteholz, Atlas. 1 



