INTERNAL MAXILLARY ARTERY. 307 



passes forwards immediately above the zygoma, between the two 

 layers of the temporal fascia, and inosculates beneath the orbicularis 

 palpebrarum with the palpebral arteries. 



The Anterior auricular arteries are distributed to the anterior por- 

 tion of the pinna. 



The Middle temporal branch passes through an opening in the tem- 

 poral fascia immediately above the zygoma, and supplies the temporal 

 muscle inosculating with the deep temporal arteries. 



11. The INTERNAL MAXILLARY ARTERY, the other terminal 

 branch of the external carotid, has next to be examined. 



Dissection. The Internal maxillary artery passes inwards behind 

 the neck of the lower jaw to the deep structures in the face ; we re- 

 quire, therefore, to remove several parts for the purpose of seeing it 

 completely. To obtain a good view of the vessel, the zygoma should 

 be sawn across in front of the external ear, and the malar bone 

 near the orbit. Turn down the zygomatic arch with the masseter 

 muscle. In doing this a small artery and nerve will be seen crossing 

 the sigmoid notch of the lower jaw, and entering the masseter muscle 

 (the masseteric). Cut away the tendon of the temporal muscle from 

 its insertion into the coronoid process and turn it upwards towards its 

 origin ; some vessels will be seen entering its under surface ; these are 

 the deep temporal. Then saw the ramus of the jaw across its middle, 

 and dislocate it from its articulation with the temporal bone. Be 

 careful in doing this to carry the blade of the knife close to the bone, 

 lest any branches of nerves should be injured. Next raise this por- 

 tion of bone, and with it the external pterygoid muscle. The artery, 

 together with the deep branches of the inferior maxillary nerve, will 

 be seen lying upon the pterygoid muscles. These are to be carefully 

 freed from fat and areolar tissue, and then examined. 



This artery (fig. 117, No. 12) commences in the substance of the 

 parotid gland, opposite the meatus auditorius externus ; it passes in the 

 first instance horizontally forwards behind the neck of the lower jaw ; 

 next, curves around the lower border of the external pterygoid muscle 

 near its origin, and ascends obliquely forwards upon the outer side of 

 that muscle ; it then passes between the two heads of the external 

 pterygoid and enters the pterygo-maxillary fossa. Occasionally it 

 passes between the two pterygoid muscles, without appearing on the 

 outer surface of the external pterygoid. In consideration of its course 

 this artery may be divided into three portions : maxillary, pterygoid, 

 and spheno-maxillary. 



Relations. The maxillary portion is situated between the ramus of 

 the jaw and the internal lateral ligament, lying parallel with the auri- 

 cular nerve; the pterygoid portion between the external pterygoid 

 muscle, and the masseter and temporal muscle. The pterygo-maxillary 

 portion lies between the two heads of the external pterygoid muscle, 

 and in the spheno-maxillary fossa is in relation with Meckel's gan- 

 glion. 



