INTERNAL MAXILLARY. 379 



The anterior auricular branches are distributed to the anterior portion of the 

 pinna, the lobule, and part of the external meatus, anastomosing with branches 

 of the posterior auricular. 



Surgical Anatomy. It occasionally happens that the surgeon is called upon to perform the 

 operation of arteriotoiny upon this vessel in cases of inflammation of the eye or brain. Under 

 these circumstances, the anterior branch is the one usually selected. If the student will con- 

 sider the relations of the trunk of this vessel as it crosses the zygomatic arch, with the surround- 

 ing structures, he will observe that it is covered by a thick and dense fascia, crossed by one or 

 two veins, and accompanied by branches of the facial and temporo-auricular nerves. Bleeding 

 should not be performed in this situation, as much difficulty may arise from the dense fascia 

 covering this vessel preventing a free flow of blood, and considerable pressure is requisite after- 

 wards to repress it. Again, a varicose aneurism may be formed by the accidental opening of one 

 of the veins covering it; or severe neuralgic pain may arise from the operation implicating one of 

 the nervous filaments which accompany the artery. 



The anterior branch is, on the contrary, subcutaneous, is a large vessel, and as readily com- 

 pressed as any other portion of the artery ; it should consequently always be selected for the 

 operation. 



The INTERNAL MAXILLARY, the larger of the two terminal branches of the 

 external carotid, passes inwards, at right angles from that vessel, to the inner side 

 of the neck of the condyle of the lower jaw, to supply the deep structures of the 

 face. At its origin, it is imbedded in the substance of the parotid gland, being 

 on a level with the lower extremity of the lobe of the ear. 



In the first part of its course (maxillary portion), the artery passes horizon- 

 tally forwards and inwards, between the ramus of the jaw and the internal late- 

 ral ligament. The artery here lies parallel with the auriculo-temporal nerve ; it 

 crosses the inferior dental nerve, and lies beneath the narrow portion of the Ex- 

 ternal pterygoid muscle. 



In the second part of its course (pterygoid portion), it ascends obliquely for- 

 wards and upwards upon the outer surface of the External pterygoid muscle, 

 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. 



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

 sel 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 this 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 fissura Glaseri, supplies the Laxator tympani, 

 and ramifies upon the membrana tympani, anastomosing with the stylo-mastoid 

 and Vidian arteries. 



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

 mater. It arises from the internal maxillary between the internal lateral ligament 

 and the neck of the jaw, and ascends vertically upwards to the foramen spinosum 

 in the spinous process of the sphenoid bone. On entering the cranium, it divides 

 into two branches, an anterior and a posterior. The anterior branch, the larger, 

 crosses the great ala of the sphenoid, and reaches the groove, or canal, in the 

 anterior inferior angle of the parietal bone ; it then divides into branches which 



