Page 1943 - Saunders Comprehensive Review For NCLEX-RN

each side of the tympanic membrane
so that the membrane does not
rupture.
D. Inner ear
1. The inner ear contains the semicircular canals, cochlea,
and distal end of the eighth cranial nerve.
2. The semicircular canals contain fluid and hair cells
connected to sensory nerve fibers of the vestibular
portion of the eighth cranial nerve.
3. The inner ear maintains the sense of balance or
equilibrium.
4. The cochlea is the spiral-shaped organ of hearing.
5. The organ of Corti (within the cochlea) is the receptor
and organ of hearing.

6. Eighth cranial nerve

a. The cochlear branch of the nerve
transmits neuroimpulses from the
cochlea to the brain, where they are
interpreted as sound.
b. The vestibular branch maintains
balance and equilibrium.

E. Hearing and equilibrium

1. The external ear conducts sound waves to the middle
ear.
2. The middle ear, also called the tympanic cavity,
conducts sound waves to the inner ear.
3. The middle ear is filled with air, which is kept at
atmospheric pressure by the opening of the auditory
canal.
4. The inner ear contains sensory receptors for sound and
for equilibrium.
5. The receptors in the inner ear transmit sound waves
and changes in body position as nerve impulses.
VI. Assessment of the Ear (see Chapter 12)
VII. Diagnostic Tests for the Ear
A. Tomography
1. Description
a. Tomography may be performed with or
without contrast medium.
b. Tomography assesses the mastoid,
middle ear, and inner ear structures
and is especially helpful in the
diagnosis of acoustic tumors.
c. Multiple radiographs of the head are
obtained.

1943