BLOOD-VESSELS OP THE HEAD. 433 



pterygoid muscle, when this artery, with the deep branches 

 of the inferior maxillary nerve, will be exposed. 



This artery commences in the substance of the parotid 

 gland, opposite the meatus auditorius externus ; passes 

 horizontally inward behind the neck of the lower jaw, 

 between it and the internal lateral ligament, and between 

 the inferior dental and gustatory nerves, to the space be- 

 tween the pterygoid muscles ; at this point it passes either 

 between these muscles, or winds over the pterygoideus 

 externus, describing a tortuous course forward, inward, and 

 somewhat upward to the tuberosity of the superior maxil- 

 lary bone, upon which it makes a considerable curve, and 

 then dips down into the pterygo-maxillary fossa, where it 

 terminates. Its branches are as follow : 



A tympanic branch, which passes through the glenoid 

 fissure to the tympanum, and also supplies the temporo- 

 maxillary articulation. The greater meningeal } or middle 

 artery of the dura mater, coming off behind the neck of the 

 lower jaw, ascends to the foramen spinale of the sphenoid 

 bone, through which it passes into the cranium, and there 

 divides into an anterior and a posterior branch, which 

 diverge and occupy the grooves on the internal surface of the 

 parietal and temporal bones, supplying the dura mater and 

 the anterior cranial bones. The lesser meningeal passes 

 through the foramen ovale to the dura mater, and is often a 

 branch of the greater. The inferior dental or maxillary, as 

 has already been described, arises opposite the greater me- 

 ningeal behind the neck, and descends between the bone and 

 internal lateral ligament to the posterior dental foramen, 

 which it enters along with the inferior dental nerve; it 

 then follows the course of the canal beneath the roots of 

 the teetYij into &at\ of which it sends successively a small 

 branch, till, arriving opposite the bicuspid, it divides into 

 two branches, one of which comes out at the anterior men- 

 tal foramen to supply the chin, and anastomose with the 

 facial ; while the other is the continued trunk going for- 

 ward as far as the symphysis, and supplying the canine 

 and incisor teeth. 

 28 



