THE OCCIPITAL BONE 



fossa — the scaphoid fossa — which originally received the primitive anterior 

 extremity of the foregut. 



On each side of the middle line are impressions for the insertions of the longiis capitis {rectus 

 capitis anterior major) and rectus capitis anterior {minor), the impression for the latter being 



Fig. 68. — The Foramen Magnum at the Sixth Year. 



Condylar foramen 



Ex-occipital portion of the 



condylejj g 



Jugular process 



Hypoglossal foramen 

 Basi-occipital portion Lof 

 the^condyle 



Basi-occipita^ 



( 



nearer to the condyle, and near the foramen magnum this surface gives attachment to the 

 anterior occipito-atlantal Ugament. Anteriorly the basilar process articulates by synchondrosis 

 with the body of the sphenoid up to twentj' years of age, after which there is complete bony 

 union. Posteriorly it presents a smooth rounded border forming the anterior boundary of 

 the foramen magnum. It gives attachment to the apical odontoid ligament, and above this 



Fig. 69. — The Occipital at Birth. (Anterior view.) 



Interparietal portion (develops in- 

 membrane) 



The interparietal and supra-occipital 

 portions form the squamous portion 

 of the adult 



Supra-occipital portion (develops in 

 cartilage) 



Ex-occipital 



Basi-occipital 



to the ascending portion of the crucial ligament. In the occipital bone at the sixth year the 

 lateral extremities of this border are enlarged to form the basilar portion of the condyles. The 

 lateral borders are rough below for articulation with the petrous portion of the temporal bones, 

 but above, on either side of the basilar groove, is a half-groove, which, with a similar half-groove 

 on the petrous portion of the temporal bone, lodges the inferior petrosal sinus. 



