254 INTERNAL MAXILLARY ARTERY. 



8. The Internal Maxillary Artery* 



Arises from the external carotid under the parotid gland, at 

 a little distance below the neck of the condyloid process of the 

 lower jaw, and extends to the bottom of the zygomatic fossa 

 varying its direction in its course. It is rather larger than the 

 temporal. 



On leaving the external carotid, it first runs downwards and 

 inwards, so as to get under c6Ver of the ramus of the jaw, then 

 inwards between the two pterygoid muscles, then upwards between 

 the two heads of the external pterygoid muscle till it reaches the 

 spheno-maxillary fossa, where it makes its last turn forwards 

 and inwards becoming horizontal. 



1. Branches given off from the Artery near the Ramus of 



the Jaw. 



A. It first sends off one or two small branches to the ear, and 

 a twig called tympanic which penetrates into the cavity of the 

 tympanum by the glenoid fissure. 



B. It also sends off a small artery called the Lesser Meningeal, 

 (meningea parva) which passes upwards, and after giving 

 branches to the external pterygoid and the muscles of the, pal- 

 ate, passes through the foramen ovale, and is spent upon the 

 dura mater about the sella turcica. 



c. It then sends off one of its largest branches, the Great or 

 middle Artery of the Dura Mater, (meningea magna) which 

 passes in a straight direction to the foramen spinale, by which 

 it enters into the cavity of the cranium. 



This artery ramifies largely on the dura mater, and makes 

 those arborescent impressions which are so visible in the 

 parietal bone. It generally divides into two great branches: 



* The general situation of this artery, and the distribution of several of its 

 most important branches, cannot be understood without a knowledge of the 

 bones through which they must pass. The student of surgery will therefore 

 derive benefit from a re-examination of these bones, and of the zygomatic 

 fossa, &c., when he studies this artery. (See vol. i. page 122.) He ought to 

 be well acquainted with this subject, if he should undertake the management 

 of necrosis of the jaw bones ; or of those fungous tumours, which sometimes 

 originate in the antrum maxillare : as well as of several other diseases of 

 these parts. 



