TRIGEMINAL NERVE. 689 



tion, also chemically. Subsequently, by reason of the abnormal attrition of the 

 teeth, ulcers form also on the healthy side. The assumption of trophic fibers is, 

 therefore, not justified. 



4. The lingual nerve (k) receives at an acute angle the chorda tym- 

 pani (i i), a branch of the facial nerve, after its exit from the tympanic 

 cavity. The lingual contains no motor fibers ; it is the sensory and tactile 

 nerve of the tongue, the anterior palatine arch, the tonsil, and the floor 

 of the mouth. Irritation of this nerve, as well as of all of the remaining 

 sensory fibers of the cavity of the mouth, excites reflex secretion of saliva. 

 In addition, the lingual is the gustatory nerve for the tip and margins 

 of the tongue (which are not supplied by the glossopharyngeal nerve), 

 for after division of the lingual nerve in man, Busch, Inzani, Lussana, and 

 others observed abolition of tactile sensation upon the entire half of the 

 tongue and of the sense of taste upon the anterior portion of the tongue . 

 These fibers, however, are, as a rule, derived from the chorda tympana, 

 as has been pointed out in the description of the facial nerve. 



According to Schiff, the lingual nerve itself contains gustatory fibers, and 

 this view is supported by cases of Erb, Senator, Ziehl, Schreier, and others. These 

 are probably exceptional cases. A. Schmidt believes that the gustatory fibers 

 reach the brain through the trunk of the fifth nerve in the following manner 

 (Fig. 243): chorda, facial trunk, connection with the lesser superficial petrosal 

 nerve (B), otic ganglion, third division, trunk of the fifth nerve. In the interior 

 of the tongue the lingual filaments are supplied with small ganglia. The lingual 

 appears to receive vasodilators for the tongue and the gums from the chorda. 

 After division of the trigeminus animals often bite the tongue, whose position 

 and movement in the mouth they are unable to feel, and in consequence injuries 

 and inflammations often result. 



5. The inferior alveolar nerve is the tactile nerve of the tongue and 

 the gums; the vasomotors pass through the superior cervical ganglion. 

 Before entering the alveolar canal, it gives off the mylohyoid nerve, 

 which supplies the motor fibers for the mylohyoid muscle and the ante- 

 rior belly of the digastric, and likewise filaments for the triangularis 

 menti and the platysma; muscle-sense fibers also probably are contained 

 in these filaments. The mental nerve, which makes its exit from the 

 mental foramen, is only the tactile branch for the chin, the lower lip, 

 and the skin at the margin of the jaw. 



6. The auriculotemporal nerve (A) sends sensory fibers to the an- 

 terior wall of the external auditory canal, the tympanic membrane, the 

 anterior portion of the ear, the adjacent temporal region, and to the 

 inferior maxillary articulation. 



In Fig. 244 the area of distribution of the trigeminal branches to the head, 

 as well as that of the cervical nerves, is indicated, and from this the nerves in- 

 volved can be determined in the presence of morbid affections (neuralgia, anes- 

 thesia) involving the parts mentioned. 



The otic ganglion is situated beneath the oval foramen upon the 

 inner aspect of the third division. There enter into it as roots: i. 

 Motor filaments from the third division itself. 2. Vasomotor fibers 

 from the plexus of the middle meningeal artery (therefore passing 

 through the superior cervical ganglion of the sympathetic). 3. From 

 the tympanic branch of the glossopharyngeal nerve filaments pass to the 

 tympanic plexus (Fig. 243, /), thence through the petrosal canal in the 

 lesser superficial petrosal nerve into the cranial cavity, then through the 

 sphenoidal fissure into the otic ganglion (m). Through the chorda 

 tympani the facial nerve is in constant connection with the ganglion, 

 just below which it passes (Fig. 243, m, i). 



44 



