Bones of the Skull. 



Planum occipitale 

 Protuberantia occipitalis externa 



Linca nuchae suprema 

 Crista occipitalis externa 

 Linea nuchae superior 



Linea nuchae inferior 

 Planum nuchale 



Foramen 

 occipitale 

 magnum 



Squama 

 occipitalis 



Fossa condyloidea 

 Canalis condyloideus 



Base of the 

 processus jugularis 



I'ars lateralis 



Processus in tra jugular! s 



Probe in 



canalis 



hypoglossi 



Tncisura jugularis 

 Condylus occipitalis 



Tuberculum pharyngeum 



Pars basilaris 



2. Occipital bone, OS OCCipitale, viewed from behind. 



The partes laterales (see also Figs. 1, 3, 59, 60 and 6366) by their medial edges 

 form the lateral borders of the great occipital foramen; the anterior portion of the lateral 

 margin is attached to the posterior angle of the petrous portion of the temporal bone and 

 helps to form the fissura petrooccipitalis ; it presents a smooth concavity, the incisura jugularis 

 which is divided by the small processus inlrajugularis into a larger lateral, posterior, and a 

 smaller medial, anterior fossa, which, with the corresponding notches of the petrous portion 

 of the temporal bone, help to form the similarly divided foramen jugular e. The lateral com- 

 partment of the jugular foramen gives passage to the internal jugular vein; the medial com- 

 partment to the sinus petrosus inf., the n. glossopharyngeus , n. vagus, n. access., gangl. sup. 

 n. glossophar., and the gangl. jugul. n. vagi. The posterior part of the lateral border, mar go 

 mastoideus, is rough and unites with the occipital margin of the mastoid portion of the tem- 

 poral bone (sutura occipitomastoidea) . At the lateral angle the processus jugularis projects 

 upward, being surrounded medianward and behind by the sulcus transversus (for the sinus 

 transversus). Median from this lies the oblong, smooth tuberculum jugular e and at the cor- 

 responding spot on the inferior surface the oval occipital condyle (condylus occipitalis), which 

 is covered with cartilage ; its anterior portion overlaps the pars basilaris ; the condyle is curved 

 so as to be convex in the sagittal and frontal direction. The long diameters of the right and 

 left condyles converge in front. Between the jugular tubercle and the occipital condyle is seen 

 the short canalis hypoglossi (0. T. anterior condyloid foramen) ; it extends from the great 

 occipital foramen obliquely forward and lateralward and gives passage to the rete canal, hypogl. 

 and the n. hypoglossus. Behind the condyle lies the condyloid fossa (fossa condyloidea) with 

 an opening (sometimes absent) known as the canalis condyloideus (0. T. posterior condyloid 

 foramen) ; this canal leads to the sulcus transversus and gives passage to the emissarium con- 

 dyloideum. On the inferior surface corresponding to the base of the jugular process is the 

 site of insertion of the m. rectus capit. lat. and sometimes a blunt projection, the processus 

 paramastoideus (not shown in the figure). 



