Quiz #2- Ears Flashcards
Where does the external auditory canal terminate?
At the tympanic membrane
What separates the external and middle ear?
The tympanic membrane
Where does lymphatic drainage from the external ear flow?
To the parotid, mastoid, and superficial cervical nodes.
Eustachian tube
Connects middle ear with nasopharyngeal and allows passage of air. Normally closed, opens with swallowing or yawning. Allows normalization of pressure on either side of the tympanic membrane so it does not rupture.
Three functions of the middle ear
- Conducts sound from outer ear to inner ear
- Protects the inner ear by reducing the amplitude of loud sounds
- Eustachian tube equalizes pressure on either side of the TM to prevent rupture.
Inner ear
Bony labyrinth, which holds the vestibule, semicircular canals, and the cochlea
Cochlea
Contains the central heating apparatus.
Three levels of hearing function
Peripheral, brainstem, cerebral cortex
Peripheral level of hearing
Vibrations are converted into electrical impulses for analysis by the brain. Electrical impulses are conducted by auditory portion of CN VIII to the brainstem.
Binaural interaction
Capacity of brainstem to locate a sound in space by using information from both ears.
Function of the cerebral cortex in hearing
Identify the sound and begin formulating an appropriate response
Causes of conductive hearing loss
Impacted cerulean, perforated TM, foreign body, pus/blood in middle ear, otosclerosis.
How to treat conductive loss
Increase amplitude of sound
Otosclerosis
Decreased mobility of the ossicles
Causes of sensorineural hearing loss
Pathology of the inner ear, CN VIII, or auditory areas of the cerebral cortex. May occur due to prebycusis, gradual nerve degeneration with aging. Increase in amplitude may not help.
