CHAPTER XIV 



THE EAR. HEARING AND EQUILIBRATION. TASTE AND 



SMELL 



The External Ear. The auditory organ in man consists of 

 three portions, known respectively as the external ear, the middle 

 ear or tympanic cavity, and the internal ear or labyrinth; the latter 

 contains the end organs of the auditory nerve. The external ear 

 consists of the expansion seen on the exterior of the head, called 

 the concha, M, Fig. 69, and a passage leading in from it, the ex- 



FIG. 69. Semidiagrammatic section through the right ear (Czermak). M, con- 

 cha; G, external auditory meatus; T, tympanic membrane; P, middle ear; o, oval 

 foramen; r, round foramen; R, pharyngeal opening of Eustachian tube; V, vesti- 

 bule; B, a semicircular canal; S, the cochlea; Vt, scala vestibuli; Pt, scala tympani; 

 A, auditory nerve. 



ternal auditory meatus, G. This passage is closed at its inner end 

 by the tympanic or drum membrane, T. It is lined by skin, through 

 which numerous small glands, secreting the wax of the ear, open. 

 The Middle Ear (P, Fig. 69) is an irregular cavity in the tem- 

 poral bone, closed externally by the drum membrane. From its 



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