ENT Pathophysiology Flashcards
Anotia
absence of the ear
hidden or “pocket ear.”
Cryptotia
Microtia
Tiny ear: diminutive ear (fetal alcohol
syndrome, gestational
diabetes, thalidomide and
isotretinion exposure).
*Often have severe conductive hearing loss
Polyotia
“mirror ear”
Stahl’s Ears
Pointed ear shape, can be reshapen
The Cochlea is Housed in the bony labyrinth of the ____ bone
temporal
Vibrations of the skull –> vibrations in cochlear _____
fluid
Sound wave conduction
Malleus, incus, stapes, oval window, scala vestibulli, movement of fluid
Fibrous membrane separating the scale tympani from scala media
Basilar Membrane
Low frequency sounds pass
farther in the cochlea through
the _____
perilymph
Translates sound waves into nerve impulses
The Organ of Corti
When basilar fibers bend toward scala
vestibuli the hair cells depolarize:
- Mechanical transduction of the cilia
- Opens K+ channels
- K+ flows from scala media fluid into the stereocilia
- Leads to depolarization and opening of voltage-gated calcium channels
- Ca++ flow in, augmenting depolarization and stimulating release of Glutamate
_____ Americans have some form of hearing loss
50 million
Most common causes of hearing loss
- cerumen impaction,
- eustachian tube dysfunction,
- age-related
Function of the Eustachian Tube and what happens if it is blocked?
1) Air-pressure equalizing valve
2) Drain for mucus lining the middle ear
If blocked → middle ear: air pocket → forms vacuum pulling ear drum inward
2 Components of the Vestibular System
Semicircular Canal System: indicate rotational movements
Otoliths: indicate linear accelerations
5 specific sensory zones
- The utricle and the saccule have flat
plaques of sensory hair cells called
maculae (2). - The ampulla of the semicircular canals contain saddle-like ridges with sensory hair cells called crests (3; aka crista ampullaris).
The ____ or the otolith membrane is a gelatinous projection into the lumen of
the ampulla, utricle and saccule that allows for easier deflection of the stereocilia of the sensory cells
cupula
Cupula is topped with _____
otolith stones
Vestibulo-ocular Reflex (VOR)
- Reflexive eye movement that stimulates the extraocular muscles by
the vestibular system - Stabilizes images on the retina during head movement
A subjective sense of
rotation of either self or
environment
Vertigo
BPPV
benign paroxsymal
positional vertigo)
calcium carbonate crystals
dislodge and migrate into
semicircular canals, occurs in
BPPV
