724 TBE NERVES, 



to discover the functional relationship that may exist between the con- 

 nections of the ear with the facial, and those of the latter nerve with the 

 auditory : but the mind perceives this relationship, and that ought to sufSoe. 



The opinion which regards the nerve of Wrisberg as the sensitive root 

 of the facial has, we believe, been more particulary accredited by the appa- 

 rent impossibility of otherwise accounting for the sensibility this nerve 

 possesses, even at its exit from the stylo-mastoid foramen — that is, before 

 contracting any anastomosis with the fijfth pair ; but this sensibility belongs 

 exclusively to the fibres of the communicating branch sent by the pneumo- 

 gastric nerve, and not to the fasciculi of the facial, as is proved by stimu- 

 lating the latter outside the aqueduct of Tallopius, after destroying the 

 pneumogastric at its origin. If it is sought to regard the intermediate 

 nerve absolutely as a branch distinct from the original filaments of the 

 auditory, and if it be determined to make it a sensitive nerve, then it must 

 at least be admitted that it does not carry its sensibility beyond the stylo- 

 mastoid foramen, and that all its filaments disappear in the ramuscules 

 furnished by the facial in its interosseous course. Otherwise, it is known 

 that M. Longet considers this nerve as forming the small superficial petrous 

 branch and the nervous filament of the stapedius muscle ; but he makes it a 

 motor branch destined to supply the muscles of the middle ear. His idea is 

 very ingenious, and would assuredly be feasible if it were possible to follow 

 the intermediate nerve from its origin to the lateral column of the medulla 

 oblongata ; but, unfortunately, this is not the case, as the small ramuscule 

 only appears to be an offshoot of the fibres proper to the auditory nerve. 



To sum up, the great superficial petrous nerve proceeds from the facial 

 by two roots : one motor, the other sensitive, assimilable, to a certain point, 

 to the roots of the spinal nerves. The first is furnished by the filaments of 

 the seventh pair ; while the second probably comes from the pneumogastric 

 nerve, and has annexed to it on its course the ganglion geniculare. The nerve 

 of Wrisberg perhaps concurs in the formation of this ganglion, but it is 

 certainly not its principal source. 



Course and Termination. — The great petrous nerve, after being detached 

 from the facial, and forming with it an obtuse angle opening outwards, 

 enters the hiatus (or aqueduct) of Fallopius — a small passage running from 

 behind forward, in the substance of the petrous bone, above the fenestra, 

 rotunda, and cochlea. Arriving at the interior of the cavernous sinus, 

 which it traverses, immersed in the blood that sinus contains, it receives a 

 branch from the ganglionic plexus there, is lodged in the Videan fissure, then 

 in the Videan canal, and in this manner gains the orbital hiatus, where it 

 separates into several branches — most frequently two — which join the 

 posterior part of Meckel's ganglion. It constitutes the motor root and 

 sympathetic filament of that ganglion. 



2. Small Superficial Petrous Nerve. — A very thin filament detached 

 from the facial to the outside of the preceding, and likewise traversing the 

 petrous bone from behind to before to enter the otic ganglion, whose motor 

 root it is. 



3. Filament op the Stapedius Muscle (Tympanic). — The facial 

 nerve, in its passage above and in front of the stapedius muscle, closely 

 adheres to it, and gives it one, perhaps several, extremely short filaments. 



4. Chorda Ttmpani (Fig. 342, 6).— This filament, also named the 

 tympano-lingnal nerve, arises at a very obtuse angle from the facial, near the 

 external orifice of the aqueductus Fallopii. It penetrates the cavity of the 

 tympanum by a particular opening, courses from its posterior to its 



