290 SKELETON OF THE EABBIT 



the tympanic bone, between it and the mastoid 

 process of the periotic. Through it the main 

 trunk of the seventh, or facial, nerve leaves 

 the skull. 



ix. The foramen lacerum posterius is an irregular 

 fissure on the under surface of the hinder 

 end of the skull, between the occipital condyle 

 and the tympanic bulla. It transmits the 

 glossopharyngeal, pneumogastric, and spinal 

 accessory nerves, and the internal jugular vein. 



X. The condylar foramina are a couple of holes 

 running obliquely through the ex-occipital, 

 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 

 surface of the tympanic bone near its in- 

 ner 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 



