Bones of the Cranium. 



Art. w. t. Sphenoid lione 



1. Occipital Bone, Os OCcipitlS, from before. 



The occipital bone is divided into 4 portions: l.basilar portion; 

 2. occipital portion; 3- and 4. two condyloid portions. 



1 . B a s i 1 a r portion. The upper surface presents a sulcus 

 for the Medulla oUongata. T h e a n t e r i o r surface borders on the body 

 of the sphenoid bone; the lateral surfaces articulate with the petrous 

 portions of the temporal bones. 



2. Occipital portion. In the middle of the anterior surface 

 is the internal occipital protuberance, Protuberantia occipitalis internet, which 

 is in the center of the Eminentia cruciata interim; the lower half of the 

 perpendicular crus is called the internal occipital crest, Crista occipitalis 

 internet (for the Sinus occipitalis and the Falx cerebelli) ; the upper half forms 

 the longitudinal sulcus (for the longitudinal sinus); the two transverse crura 

 contain the transverse sulcus (for the lateral sinus and attachment of the 

 Tentorium cerebelli). In both upper fossae lie the occipital lobes of the cereb- 

 rum ; in the lower the 2 hemispheres of the cerebellum. 



1* 



