FORAMEN MA GNUM 



27 



The basi-occipital is a quadrilateral plate of bone. Its sii])erior surface is 

 concave for tlic incdulla olylongata. Inferiorly it is rough, and presents the 

 pharyngeal tubercle, to which the median portion of the fibrous bag of the pharynx 

 is attaclied. in front of the tubercle near the anterior end of the bone there is 



Fig. 32. — Ckkebral Surface of the Occipital, showing an Occasional Disposition <jf 



THE Channels. 



VERMIFORM FOSSA 



POSTERIOR CONDYLOIO 



FORAMEN 



ANTERIOR CONDYLOID 



FORAMEN 



often a shallow fossa, which originally received the primitive anterior extremity of 

 the foregut. The rectus capitis anticus major and minor- muscles are inserted into 

 this surface. Anteriorly the basi-occipital is, in the adult, ankylosed to the basi- 

 sphenoid. Posteriorly it has a smooth, rounded, narrow, concave border forming 

 the anterior boundary of the foramen magnum. 



Fig. 33. — The Fokamen Magnim at the Sixth Year. 



POSTERIOR CONDYLOID FORAMEN 



ex-og:ipital portion of the 



CONDYLE 



JUGULAR PROCESS 



ANTERIOR CONDYLOID FORAMEN 

 BASI-OCCIPITAL PORTION OF THE 

 CONDYLE 



BASI-OCCIPITAL 



The extremities of this liorder enlarge to join the ex-occipitals, and form tlie 

 anterior extremities of the condyles. The lateral l)orders are rough below, and 

 articulate witli tlie inferior borders of the petrosals. Aliove they are grooved for the 

 inferior petrosal sinus. 



The foramen magnum is oval in shaiie. with its major axis in the long a.xis of 



