Figure 13-6. A frontal section of the human ear.
13-11. THE EXTERNAL EAR
The external ear begins with a funnel-like auricle. This auricle serves as a
collector of the airborne waves and directs them into the external auditory meatus. At
the inner end of this passage, the waves act upon the tympanic membrane (eardrum).
The external auditory meatus is protected by a special substance called earwax
(cerumen).
13-12. THE MIDDLE EAR
a. Tympanic Membrane. The tympanic membrane separates the middle and
external ears. It is set into mechanical oscillation by the airborne waves from the
outside.
b. Middle Ear Cavity. Within the petrous bone of the skull is the air-filled
middle ear cavity.
(1) Function of the auditory tube. Due to the auditory tube, the air of the
middle ear cavity is continuous with the air of the surrounding environment. The
auditory tube opens into the lateral wall of the nasopharynx. Thus, the auditory tube
MD0007
13-11
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