MIDDLE EAR + CN VII Flashcards
Define the labyrinthine artery.
This is also known as the internal auditory artery and supplies the inner ear such as the vestibular apparatus and cochlea.
What is the function of the tensor tympani and what nerve innervates it?
This is a muscle that is responsible for reducing the intensity at the tympanic membrane for loud sounds. The motor fibers of mandibular division (V3) of trigeminal nerve innervates it.
What nerve innervates the stapedius and what does the muscle do?
The nerve to the stapedius arises from the facial nerve (CN VII). This muscle stabilizes the stapes by reducing vibration therefore acting as a better protective mechanism to sensory hair cells from exposure of loud noises.
Describe Hyperacusis.
A lesion of the facial nerve just proximal to the stapedius nerve can paralyze the stapedius and heighten sensitivity to sounds.
If a patient is experiencing Conductive Hearing loss, he or she will experience bone conduction to be ____ than air conduction at the affected side.
Greater (>) than
How does the Weber test differ from the Rinne test in terms of localization of sounds?
The Weber test allows us to localize to the place where there is hearing loss, but the Rinne test allows us to evaluate if it’s a conductive or sensorineural hearing loss.
Describe Bell’s Palsy and what physicians can use to test for it.
This is caused by a lesion to the facial nerve (CN VII). It features hyperacuisis and facial weakness at the affected side. Doctors can test the blink reflex (VII), tongue protrusion (XII), the gag reflex (IX and X) or the elevation of the palate (X) to evaluate associated symptoms of nearby nerve lesions.
When evaluating the ears for hearing loss, what should the patient feel during a Weber test when a tuning fork is placed at the midline?
The patient should feel a vibration on both sides of the head, with no lateralization of that vibration.
When evaluating the ear with the Rinne test, a physician should observe in a typical patient that bone conduction is ________ than air conduction.
Less (
A doctor performs the Rinne test to test for conductive hearing loss. He finds that a patient perceives air conduction to be greater than bone conduction. What event in the middle ear may explain this presentation?
Disarticulation of the ossicles (such as the malleus from the incus or incus from stapes)
Define the functions of the saccule and utricle.
The utricle detects horizontal translatory movement. The saccule detects vertical translatory movement.
How can Otitis media progress into meningitis?
Prolonged ear infection through otitis media can erode the tegmen tympani which is the roof of the inner ear and into the MCF.
What is the function of the middle ear amplifier?
This adds 30 decibels to whatever is being heard, to compensate for the lost vibration during sound transduction (from airborne vibration into an aqueous environment).
How does conductive hearing loss differ from a sensorineural hearing loss?
A conductive hearing loss is an external or middle ear issue, where the stimulus is not being conducted well into the inner ear. This can be due to earwax or disarticulation of the ossicles. Sensorineural hearing loss has to do with an issue of the CN VIII or the inner ear apparatus.
The Eustachian tube connects the ________ and _________ cavity. It functions to ________ pressure between the _____ ear and outside world when open. The _______ _______ muscle opens this normally closed tube when we swallow.
Pharynx, Tympanic cavity;
Equalize, middle ear;
Levator Palati
