i8o HEAD AND NECK 



motor root of the mandibular nerve ; but it contains also a 

 few sensory fibres which are afterwards distributed by its 

 buccinator branch. 



It passes downwards and forwards on the medial side of 

 the external pterygoid muscle, and it gives off the following 

 branches : 



1. Masseteric. 3. External pterygoid. 



2. Two deep temporal. 4. Buccinator. 



Nervus Massetericus. The masseteric nerve runs hori- 

 zontally above the external pterygoid muscle, and, after pass- 

 ing through the incisura mandibulae (O.T. sigmoid notch), 

 posterior to the temporal muscle, it enters the posterior and 

 upper part of the deep surface of the masseter. Before 

 reaching the masseter it gives one or two twigs to the 

 mandibular joint. 



Nervi Temporales Profundi. There are usually two 

 deep temporal nerves, anterior and posterior. The posterior 

 nerve is the smaller of the two ; it frequently arises by a 

 common root with the masseteric. Both deep temporal 

 nerves pass laterally above the external pterygoid, and then 

 turn upwards on the medial wall of the temporal fossa. They 

 supply the temporal muscle. 



Nervus Buccinatorius. The buccinator nerve (O.T. long 

 buccal) is the largest of the branches arising from the 

 anterior division. It proceeds laterally between the two 

 heads of the external pterygoid muscle, and then runs down- 

 wards and forwards under cover of the temporal muscle, and 

 under cover of the anterior border of the masseter also, to 

 reach the outer surface of the buccinator muscle. There it 

 unites with branches of the facial nerve to form the buccal 

 plexus, from which branches are distributed to the mucous 

 membrane and skin of the cheek. 



The buccinator nerve is a sensory nerve, and all the sensory 

 fibres in the anterior division enter into its composition. A 

 few motor fibres, however, are also prolonged into it; they 

 leave it in two branches, viz., (i) in the nerve to the external 

 pterygoid, which, as a rule, arises in common with the buc- 

 cinator nerve; and (2) in the anterior deep temporal nerve 

 to the temporal muscle. The anterior deep temporal nerve 

 springs from the buccinator nerve, either before or after it 

 has reached the lateral surface of the external pterygoid, and 

 proceeds upwards to supply the anterior part of the temporal 



