hearing and balance

Hearing and balance
Objectives: after you finish this lecture you should know:
? Describe the components and functions of the external, middle, and inner
ear.
? Describe the way that sound waves are converted into impulses generated in
hair cells in the cochlea.
? Explain the roles of the tympanic membrane & the auditory ossicles
(malleus, incus, and stapes) in sound transmission.
? Explain how auditory impulses travel from the cochlear hair cells to the
auditory cortex .
? Explain how pitch & loudness are coded in the auditory pathways.
? Describe the various forms of deafness and the tests used to distinguish
between them.
? Explain how the receptors in the semicircular canals detect rotational
acceleration and how the receptors in the saccule and utricle detect linear
acceleration.
? List the major sensory inputs that provide the information that is synthesized
in the brain into the sense of position in space.
Introduction
Our ears not only let us detect sounds, but they also help us maintain balance.
Receptors for two sensory modalities (hearing and equilibrium) are housed in
the ear. The external ear, the middle ear, and the cochlea of the inner ear are
concerned with hearing. The semicircular canals, the utricle, and the saccule
of the inner ear are concerned with equilibrium. Both hearing and equilibrium
rely on a very specialized type of receptor called a hair cell