Nursing 109

N109: Foundations in Nursing Practice Study Guide

Ear structures:

Structure and function of the ear: Ear Structure Function Pinna Sometimes called the auricle, the pinna is the visible outer ear that collects the sound and directs it into the auditory canal. Auditory canal Also called the outer ear canal, the auditory canal is the tube through which sound travels to the tympanic membrane. Tympanic Membrane (TM) Also called the eardrum, it is a slender elastic membrane that vibrates when sound waves are received from the auditory canals. These sound waves are then transmitted to the ossicles of the middle and inner ear. Malleus Also called the hammer, it is one of the three bony ossicles that passes vibrations from the TM to the incus. Incus Also called the anvil, it is one of the three bony ossicles that receives vibrations from the malleus and passes it to the stapes. Stapes Also called the stirrup, it is one of the three bony ossicles that receives vibrations from the incus and passes it to the cochlea. Semicircular canals These three canals are fluid filled tubes attached to the cochlea, and are important in maintaining a sense of balance. Eustachian tube This tube from the middle ear to the nasopharynx allows outside air to pass through, equalizing pressure on both sides of the TM. In changes of altitude, the pop heard in the ear is pressure equalizing through the Eustachian tube. Cochlea This spiral shaped fluid filled structure in the inner ear is lined with cilia (tiny hairs) that move when the vibration is received and cause a nerve impulse to form. Auditory nerve The nerve impulse created in the cochlea is transferred to the auditory nerve for transmission to the brain.

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