276 HEAD AND NECK 



the cranium by accompanying the middle meningeal artery 

 through the foramen spinosum. It supplies the dura mater. 



The nerve to the internal pterygoid will be found passing 

 under cover of the posterior border of the internal pterygoid 

 muscle at its upper end. In close relation to the root of 

 this nerve is the otic ganglion. 



From the two terminal divisions of the mandibular 

 trunk the chief branches of distribution arise. The anterior 

 division is much the smaller of the two, and is composed almost 

 entirely of motor fibres derived from the motor root of the 

 trigeminal nerve. The only sensory fibres which it contains 

 are those which form the buccinator nerve. It gives off the 

 following branches : 



1. Masseteric. 3. External pterygoid. 



2. Two deep temporal. 4. Buccinator. 



The large posterior division is chiefly sensory. It contains 

 only a very few fibres from the motor root, and these are 

 prolonged into its inferior alveolar branch, and afterwards 

 come off in the form of the mylo-hyoid nerve. The branches 

 of the posterior division are: (i) auriculo-temporal ; (2) 

 inferior alveolar ; (3) lingual. 



Nervus Massetericus. The masseteric nerve runs hori- 

 zontally above the external pterygoid muscle, and, passing 

 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 

 temporo-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 upward 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 of the mandibular nerve. It proceeds 

 laterally between the two heads of the external pterygoid 

 muscle, and then runs downwards and anteriorly under 

 cover of the temporal muscle, and under cover of the anterior 



