DIGESTION *45 



traction of the elevator muscles of the lower jaw. When the occasion arises 



or the introduction of food, the mouth is opened by the depressor muscles; 



ter the food is introduced into the mouth it is again closed and that 



combination of muscle contractions initiated which when continued results 



the nerve mechanism for 

 mastication are shown in the following table: 



Efferent Nerves. 

 t o< * 



the trigeminal nerve. 2 HypO gi ossa l. 



2. Glosso-pharyngeal. 3 Facial or portio dura. 



The Efferent Nerves.-The efferent nerves that transmit nerve im- 

 pulses to the various muscles of mastication are the small root of the 



* after emerging from .the cavity 



'ttfssS&SG 



the food develops in afferent nerves are rea ved by me That 



e 



thus falling into the category f J e ^^ c Se?fc indicated by the 

 the masticatory movements are ^^^^^ volitional effort that 

 fact that they will be '? has been directed to some 



of the tongue and mouth. stimulation of which 



The Afferent Nerves.-The afferent : nerv , branches o f the 



