FACIAL NERVE. 695 



The chorda contains secretory fibers for the sublingual and sub- 

 maxillary glands and vasodilators for these and the tongue. From 

 the observations of numerous investigators it has, further, been estab- 

 lished that the chorda tympani contains also gustatory fibers for the 

 margin and the tip of the tongue, which, further on, it gives off to the 

 tongue in the course of the lingual. Urbantschitsch observed a man 

 whose chorda was exposed and in whom irritation of the nerve in the 

 tympanic cavity caused gustatory sensations, together with sensory im- 

 pressions. 



It must, therefore, be accepted as established that the gustatory 

 fibers of the chorda originate in the glossopharyngeal nerve. They may 

 enter the chorda : i . Through the intermediary portion of Wrisberg, and 

 this view has recently received general acceptance. 2. A further pos- 

 sible means of communication is afforded beyond the stylomastoid fora- 

 men, namely, through the communicating branch with the glossopharyn- 

 geal nerve (Fig. 243, e), which passes from the nerve last mentioned into 

 that branch of the facial that at the same time contains the motor fibers 

 for the stylohyoid muscle and the posterior belly of the digastric (Henle's 

 styloid nerve). This nerve gives off also, perhaps, muscle-sense fibers for 

 the stylohyoid muscle and the posterior belly of the digastric. In addi- 

 tion, it is assumed that by means of this anastomosis motor fibers from the 

 facial are brought to the glossopharyngeal. A third point of union be- 

 tween the ninth and seventh nerves is situated in the tympanic cavity : 

 the tympanic branch of the glossopharyngeal (/) that enters the tympanic 

 cavity is connected in the tympanic plexus with the lesser superficial 

 petrosal nerve (ft), which is derived from the geniculate ganglion of the 

 facial. The lesser superficial petrosal nerve may thus transmit gustatory 

 fibers to the geniculate ganglion of the facial. It may, however, convey 

 the gustatory fibers first to the otic ganglion, which is constantly con- 

 nected with the chorda tympani. Finally, a fourth connection has been 

 described as taking place through a filament (~) from the petrous gan- 

 glion of the ninth nerve directly to the facial trunk in the Fallopian 

 canal. 



The chorda contains vasodilators for the anterior two-thirds of the 

 tongue. 



Mention should be made here of the remarkable fact that from i to 3 

 weeks after division of the hypoglossal nerve, irritation of the chorda 

 causes movements in the paralyzed tongue. These movements are 

 feeble and tardy, in comparison with those resulting from hypoglossal 

 stimulation. The phenomenon is explained on p. 559. It depends essen- 

 tially upon an increased supply of blood, in conjunction with an aug- 

 mented secretion of lymph, as a result of which the corresponding half 

 of the tongue becomes edematous. Heidenhain designates this action 

 pseudomotor . 



With respect to Heidenhain 's interpretation it should be recalled that mus- 

 cular contraction depends on swelling through the taking up of fluid. The pseudo- 

 motor contraction has a latent stage ten times as long as that of hypoglossal 

 irritation. A single moderate induction-shock is ineffective, as is also chemical 

 irritation; nevertheless reflex stimulation may occur through various sensory 

 nerves. Nicotin first stimulates, then paralyzes, movement excited through the 

 chorda. The chorda transmits motor impulses even for a short time after sup- 

 pression of the circulation. The pseudomotor contraction gives rise to no muscular 

 sound. 



5. Even before the chorda is given off the trunk of the facial enters 



