Physiology of hearing

Transmits vibrating column of air


Vibrates and transmits movement to ossicles


Move in a lever action to cause vibration of the oval window


Converts oval window vibrations to electrical signals


Nerve impulses transmitted to cortex in response to cochlear activity


Nerve impulses perceived as sound


External

Oval

Auditory

Auditory

Transformation of environmental sound to perception of hearing at the cortex


Scala vestubuli (perilymph)

Figure 2.2

The fine structure of the cochlea showing hair cells and the auditory nerve

(a)  Cross-section of the cochlea. The scala tympani and scala vestibuli are filled with perilymph, and the scala media is filled with endolymph. It is separated from the scala tympani by Reissner's membrane and from the scala vestibuli by the basilar membrane which supports the organ of Corti

(b)  Diagram representing the organ of Corti. The entire length of the cochlea contains one row of inner hair cells and three rows of outer hair cells



The ear has two physiological functions: hearing and the maintenance of balance (see Chapter 12).

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