TEi: COMMON CAROTID ARTERIES. 673 



branches of the maxillary nerve, and anastomosing with the inferior coronary 

 artery. 



Before penetrating the maxilla, this artery furnishes divisions to the internal 

 pterygoid and mylo-hyoid muscles. 



In the interior of the maxillo-dental canal, it gives off diploic branches, as 

 weU as twigs, to the roots of the molar teeth and the alveolar membrane. 



2. Pterygoid Arteries (Fig. ;381, 29).— It maybe said, in a general manner, 

 that the two pterygoid muscles receive their arteries from all the vessels passing 

 near them ; though there are two, and sometimes three, branches more especially 

 intended for them. These branches — or, properly speaking, pterygoid arteries — 

 arise from the middle of the second curvature of the internal maxillary, either 

 at an acute or right angle, and enter the pterygoid muscles, after a short course 

 forward and downward on the external tensor palati muscle— this, and its fellow, 

 the internal muscle, also receiving some branches. 



3. Tympanic Artery (Fig. 381, 30). — A very thin and small, but constant 

 artery, gliding along the surface of the guttural pouch, accompanying the 

 tympano-lingual nerve, and penetrating the tympanic cavity by a foramen 

 situated at the base of the styloid process of the temporal bone (the fissura 

 Glaseri). It throws off ramuscules to the wall of the guttural pouch and the 

 trigeminal nerve ; these often arise directly from the trunk of the internal 

 maxillary artery, beside the tympanic branch. 



4. Spheno-spinous or Great Meningeal Artery (Fig, 881, 31). — Com- 

 mencing at an obtuse angle, opposite the pterygoideal vessels, this artery lies 

 against the sphenoid bone, near the temporal insertion of the tensor palati 

 muscles, is directed backwards and upwards, enters the cranium by the foramen 

 lacerum basis cranii, outside the inferior maxillary nerve, passes beneath the dura 

 mater, and soon after engages itself in a particular foramen in the parieto- 

 temporal canal, where it anastomoses by inosculation with the mastoid artery. 



Before penetrating this canal, the spheno-spinous artery gives off a meningeal 

 branch, the ramifications of which, destined to the dura mater, stand in relief on 

 that membrane, and creep along in the small grooves channeled on the inner 

 surface of the cranium. 



The volume of this vessel is subject to the greatest variations, and is always 

 in an inverse proportion to that of the mastoid artery. 



5. Posterior Deep Temporal Artery (Fig. 381, 32). — This arises at a 

 right angle, immediately before the entrance of the internal maxillary artery into 

 the subsphenoidal canal. It ascends on the temporal bone, in the temporal 

 muscle, passing in front of the temporo-maxillary articulation, which it turns 

 round to be inflected backwards. Tliis vessel communicates with the masseteric 

 artery by a fine division, which traverses the sigmoid notch in the maxillary 

 bone. 



6. Anterior Deep Temporal Artery (Fig. 381, 33). — Springing at a 

 right angle, like the preceding, in the interior of the subsphenoidal canal, this 

 artery escapes by the superior branch of that conduit, ascends against the bony 

 wall of the temporal fossa, along the anterior border of the temporal muscle, 

 in which it is almost entirely expended. It gives some ramuscules to the adipose 

 tissue of the temporal fossa. Its terminal extremity arrives beneath the internal 

 parieto-auricularis muscle, and ramifies in it and in the skin of the forehead. 



7. Ophthalmic Artery (Fig. 381, 34). — This vessel has a somewfiat 

 singular arrangement. After being detached from the internal maxillary in the 



