6i6 



THE NERVOUS SYSTEM 



root. The root describes a loop around the nucleus of the sixth nerve, 

 running forward for some little distance dorsal to the nucleus, then descend- 

 ing vertically, passing to the outside of its own nucleus, between it and the 

 descending root of the fifth nerve. It emerges at the lower margin of the 

 pons, lateral to the sixth nerve, opposite the front edge of the groove between 

 the olivary and restiform bodies. The second or sensory root is smaller and 

 is called the pars intermedia, figure 412. It is the portion which is connected 



V.G 



I.C. 



Sty. hy 



FIG. 412. The Seventh Nerve and Its Branches. VII, Facial nerve; P.I, pars 

 intermedia; VIII, auditory nerve; Aq.Fal, aqueduct of Fallopius; G.G, geniculate ganglion; 

 E.S.P, external superficial petrosal nerve; M.M, middle menmgeal artery; G.S.P, great 

 superficial petrosal nerve; G.P.D, great deep petrosal nerve; I.C, internal carotid artery; 

 Vid, Vidian nerve; M.G., Meckel's ganglion; Ty.Pl, tympanic plexus; S.D.P, small deep 

 petrosal nerve; G.Ph, Glosso-pharyngeal nerve; Ty, tympanic branch; S.S.P., small super- 

 ficial petrosal nerve; O.G., optic ganglion; Stap, nerve to stapedius; C.T, chorda tympani 

 nerve; Z,, lingual nerve; A.Va, communication with auricular branch of vagus; P. A, 

 posterior auricular nerve. Sty.hy, nerve to stylo-hyoid; Di, nerve to digastric (posterior 

 belly); T.F, temporal-facial division; C.F, cervico-facial division; T, temporal; M, malar; 

 I.O, infra-orbital; B, buccal, S.M, supra-mandibular; I.M, infra-mandibular branches. 

 (Cunningham.) ^ \ {f . ^ 



with the chorda tympani and geniculate ganglion, figure 413. The pars 

 intermedia terminates within the brain in the fasciculus solitarius in com- 

 mon with the glosso-pharyngeal. 



Functions. The seventh nerve is the motor nerve of all the muscles of the 

 face, including the platysma, but not including the muscles of mastication. 

 It supplies the stapedius, the stylo-hyoid and the posterior part of the 

 digastric. Its branches also supply the rudimentary muscles of the external 

 ear. 



Fibers from the chorda tympani are distributed to the submaxillary 

 gland and produce secretion when stimulated. 



