142 NERVOUS SYSTEM. 



is chiefly sensitive, but contains some motor filaments, 

 branches are sent to the mylo-hyoid muscle, and to the an- 

 terior belly of the digastric. In addition, the motor branch 

 of the fifth sends filaments to the tensor muscles of the ve- 

 lum palati. 



The above description shows, in general terms, the dis- 

 tribution of the nerve of mastication, without taking into 

 consideration its various anastomoses, the most important 

 of which are with the facial. Physiological experiments 

 have shown that the buccinator muscle receives no motor 

 filaments from the fifth, but is supplied entirely by the facial. 

 Mayo found that pinching the branch of the fifth which 

 penetrates the buccinator muscle produced no action upon 

 it. 1 Longet has galvanized the buccal branch of the fifth 

 without producing contraction of this muscle, which always 

 contracts upon galvanizing the facial. 2 The buccal branch 

 of the fifth sends motor filaments only, to the external ptery- 

 goid and the temporal, its final branches of distribution be- 

 ing sensitive and going to integument and mucous mem- 

 brane. 



In another volume we have given a table of the muscles 

 of mastication, with a description of their action. 3 It will 

 be seen by this table that the following muscles depress 

 the lower jaw ; viz., the anterior belly of- the digastric, 

 the mylo-hyoid, the genio-hyoid, and the platysma myoides. 

 Of these, the digastric and the mylo-hyoid are animated by 

 the motor root of the fifth ; the genio-hyoid is supplied by 

 filaments from the sublingual ; and the platysma myoides, by 

 branches from the facial and from the cervical plexus. All 

 of the muscles which elevate the lower jaw and move it lat- 

 erally and antero-posteriorly ; viz., the temporal, masseter, 

 and the internal and external pterygoids, the muscles most 



1 MAYO, Anatomical and Physiological Commentaries, Number il, London, 

 1823, p. 8. 



8 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 663. 

 8 See vol. ii., Digestion, p. 147, et seq. 



