The diseases of the ear and their treatment . ngeal nerve chiefly supplies the middle earwith sensory fibres. Its small branch, the tympanic or nerve ofJacobson, enters through the floor of the tympanic cavity, extendsin a groove, frequently partly bridged over, to the promontory,and then distributes itself upon the mucous membrane of the tym-panum. This nerve is connected on the one hand with the oticganglion of the trigeminus by the small superficial petrosal nerve,which extends below the canal of the tensor tympani muscle, andon the other hand with the sympathetic by small twigs from theint
The diseases of the ear and their treatment . ngeal nerve chiefly supplies the middle earwith sensory fibres. Its small branch, the tympanic or nerve ofJacobson, enters through the floor of the tympanic cavity, extendsin a groove, frequently partly bridged over, to the promontory,and then distributes itself upon the mucous membrane of the tym-panum. This nerve is connected on the one hand with the oticganglion of the trigeminus by the small superficial petrosal nerve,which extends below the canal of the tensor tympani muscle, andon the other hand with the sympathetic by small twigs from theinternal carotid plexus. The system of nerves thus consisting offibres of the glosso-pharyngeal, trigeminus, and sympathetic iscalled the tympci7iic plexus. The facial nerve gives off the chorda tympani in its canal beforeit issues at the stylo-mastoid foramen. It enters the tympanum in 124 DISEASES OF THE MIDDLE EAR. a direction curving forward and downward upon the inner surfaceof the posterior pocket of the membrana tympani, passes above the. Fig. 28. Fig. 29. F. Fossa sigmoidea. M. Mealus auditorius externus. C. Cavum cranii. tendon of the tensor tympani, and over the neck of the malleus,leaving the tympanum by descending through the fissure of Glaser,and then uniting with the lingual branch of the trigeminus. Thechorda tympani contains gustatory fibres supplying the anterior partof the tongue, and also fibres influencing the secretion of the sali-vary glands. By experiments on animals, Gelle and Berthold haveproved that the tympanic cavity is supplied with trophic fibres bythe trigeminus. The latter in particular ascertained by numerousexperiments that inflammatory symptoms are produced in the middleear by section of the trigeminus, either in its course or at its changes are caused in the tympanum by removal of the glosso-pharyngeal or by extirpation of the superior cervical ganglion. Posteriorly and externally the tympanic cavity is connectedwith the air-cells of t
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