456 



ARTERIES. 



being covered by the ramus of the lower jaw, and lower part of the Temporal 

 muscle. 



In the third part of its course (spheno-maxillary portion), it approaches the 

 superior maxillary bone, and enters the spheno-maxillary fossa, in the interval 

 between the processes of origin of the External Pterygoid, where it lies in rela- 

 tion with Meckel's ganglion, and gives off its terminal branches. 



Fig. 277. The Internal Maxillary Artery, and its Branches. 



Fig. 278. flan of the branches 



luciltVf 



Peculiarities. Occasionally, this artery passes between the two Pterygoid muscles. The 

 vessel in this case passes forwards to the interval between the processes of origin of the External 

 Pterygoid, in order to reach the maxillary bone. Sometimes the vessel escapes from beneath 

 the External Pterygoid by perforating the middle of that muscle. 



The branches of this vessel may be divided into three groups, corresponding 

 with its three divisions. 



1. Branches from the Maxillary Portion. 



Tympanic. Small Meningeal. 



Middle Meningeal. Inferior Dental. 



The tympanic branch passes upwards behind the articulation of the lower jaw, 

 enters the tympanum through the fissure of Grlaser, supplies the Laxator Tym- 

 pani t and ramifies upon the membrana tympani, anastomosing with the stylo- 

 mastoid and Yidian arteries. 



The middle meningeal is the largest of the branches which supply the dura 

 mater. It arises from the internal maxillary between the internal lateral liga- 



