COMPARATIVE ANATOMICAL AND PHYSIOLOGICAL 

 STUDIES OF GUSTATORY MECHANISMS* 



R. L. KiTCHELL 



Department of Veterinary Anatomy, College of Veterinary Medicine, 

 University of Minnesota, St. Paul 1, Minnesota 



During the course of previous investigations variations in the route and 

 structure of the chorda tympani nerve were observed within and among 

 species. A study was initiated which was directed toward describing the 

 gross and microscopic structure of the chorda tympani nerve and the 

 peripheral distribution of the lingual branch of the mandibular nerve in 

 selected domestic animals. A detailed report of the results of this study 

 will be published elsewhere (Engebretsen and Kitchell, unpublished). 

 Figures 1-4 illustrate some of the results of the gross anatomical studies. 

 In studies of the neural responses in the chorda tympani following the 

 application of solutions to the tongue, the chorda tympani nerve is usually 

 exposed in the infratemporal fossa by resection of the mandible caudal to 

 the last molar tooth and disarticulation at the temporomandibular articula- 

 tion. Removal of the articular disk facilitates observation of the chorda 

 tympani nerve. Certain comparative anatomical features are of particular 

 importance. The chorda tympani nerve in the pig (Fig. 2) is closely asso- 

 ciated with the mandibular branch of the trigeminal nerve from the point 

 the mandibular nerve leaves the cranial cavity through the oval notch of the 

 foramen lacerum until the chorda tympani nerve intermingles with the 

 lingual branch of the mandibular. In order to locate the chorda tympani 

 nerve in the pig the auriculo-temporal and mandibulo-alveolar nerves must 

 be severed and reflected rostrally. The nerve can be seen by dissecting 

 the mandibulo-alveolar nerve centrally. The chorda tympani nerve 

 appears as one or two fascicles crossing the medial surface of the mandibulo- 

 alveolar nerve at right angles to other fascicles in the mandibulo-alveolar 

 nerve. The chorda tympani in the pig has only a very short portion 

 whereby it is completely separate from the mandibular nerve before the 

 chorda tympani enters the petrotympanic fissure. 



* Approved for publication as a scientific journal series paper no. 4928, Minnesota 

 Agricultural Experiment Station, St. Paul Minnesota. 



The author acknowledges with appreciation the technical assistance of Miss Margie 

 Shnts who prepared the microscopic sections and did the photomicrographic techniques 

 used as a part of this report. 



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