282 SKELETON OF THE EAEBIT 



just in front of the condyle. They transmit 

 the two divisions of the hypoglossal nerve, and 

 are best seen through the foramen magnum. 



b. Other important apertures in the skull. 



i. The anterior narial opening is at the anterior 

 end of the skull, and is bounded by the nasals 

 and the premaxillse. It is single in the dried 

 skull, but divided in the natural condition by 

 the vertical cartilaginous septum narium. 



ii. The lacrymal foramen is formed by a deep 

 notch in the outer border of the lacrymal 

 bone, completed in front by the orbital process 

 of the maxilla. It leads into the canal along 

 which the lacrymal duct runs into the nose. 



iii. The pituitary foramen is a median hole, per- 

 forating the floor of the pituitary fossa in the 

 centre of the basi-sphenoid : in the natural 

 condition it is closed by membrane. 



iv. The carotid foramen perforates the ventral sur- 

 face of the tympanic bone near its inner 

 border, close to the occipital condyle : 

 through it the internal carotid artery enters 

 the skull. 



V. The opening of the Eustachian canal is on the 

 under surface of the skull, at the anterior and 

 inner angle of the tympanic bone, imme- 

 diately behind and to the inner side of the 

 foramen lacerum medium : through it the 

 Eustachian tube passes from the tympanic 

 cavity to the posterior narial chamber. 



vi. The external auditory aperture is the large 

 upwardly directed opening of the neck of the 

 tympanic bone, round the edge of which the 

 cartilage of the external ear is attached. 



vii. The foramen magnum is the large median 

 hole at the hinder end of the skull, surrounded 

 by the bones of the occipital segment. It is 



