Auditory and Vestibular System ppt 26 Flashcards
What are the anatomical components of the middle ear?
Auditory ossicles:Transmit and amplify vibrations from tympanic membrane to oval window.
Auditory (eustachian) tube:Equalizes air pressure on both sides of tympanic membrane.
What are the anatomical components of the internal ear?
Cochlea: Contains a series of fluids, channels, and membranes that transmit vibrations to spiral organ (organ of Corti), the organ of hearing; hair cells in spiral organ produce receptor potentials, which elicit nerve impulses in cochlear branch of vestibulocochlear (VIII) nerve.
What is the mechanism of sounds conduction
mechanical movement of stereocillia causes depolarization of hair cells.
a downward displacement causes hyperpolarization
What is the auditory pathway?
Cochlear nerve–> cerebellopontine angle (lateral pons)–> superior olivaery, trapezoid, l. lemmiscus, inf. colliculus, medial geniculate body, super temporal gyrus
What is the tympanic reflex?
Tensor tympani and stapedius muscles cause the malleus be pulled inward
What is the issue with a Eustachian tube dysfunction?
altered pressure= TM stretch= pain
What is a conduction deafness hearing defect?
interruption of the passage of sound waves through the external or middle ear
Obstruction Ostoclerosis Otitis Media (inflammation)
What is a nerve deafness hearing defect?
Disease of the cochlea, cochlear nerve, or central auditory pathway (acoustic neuroma)
Presbycusis (aging. most common cause of hearing loss)
Acoustic Neuroma
Weber Test
Tunning fork top head
unilateral louder sound sound:
conduction-bad ear
sensorineural- good ear
Rinne Test
A>B
air/ bone conduction
Schwabach Test
compares bone conduction to a normal person
What are the anatomical components of the vestibular apparatus?
Semicircular ducts. Otolithic Organs (saccule and utricle)
What is the function of the semilunar ducts?
Contain crustal (hair cells) that respond to rotational Acceleration and declaration of movement,
What is the function of the utricle?
horizontal acceleration
static equilibrium in relation to the force of gravity. most sen. when head is up right
What is the function of the saccule?
vertical acceleration
static equilibrium in relation to the force of gravity. most sen. when head is horizontal
What kind of crystals lie atop hair cells in the otolithic organs?
Calcium Carbonate crystals called otoconia
What are the fluids of the labyrinth?
Perilymph-Extracellular fluid:communicates with subarachnoid via aqueduct
Endolymph-Intrecellular fluid: recreated by the stria
What is the role of vestibular apparatus in posture?
- maintenance of equilibrium & balance.
- hair cells in vestibular apparatus activates VIII.
- Sensory fibers transmit impulses to cerebellum
What is the 3 neuron arc in the VOR
oculomotor nuclei, vestibular nuclei, and vestibular ganglion.
Caloric Nystagmus
Mnemonic COWS Cold, Opposite; Warm, Same
watch vide
Internuclear opthalmoplegia
definite in adduction and contralateral abducting nystagmus
horizontal diplopia
trouble tracking fast objects
watch video: https://www.youtube.com/watch?v=MWJz75R01s4
Motion sickness
caused by stimulation of the semicircular canals during motion,
ntihistamines that affect the neural pathways from the vestibule.
Meniere Disease
an inner ear disease associated with an increase in endolymphatic fluid pressure. Characterized by episodic attacks of vertigo, tinnitus, hearing loss, horizontal nystagmus
Tinnitus
- noises such as ringing, clicking, whistling, or booming in the ears.
- disorders in the middle or inner ear
Vertigo
- sensation of turning or rotation
- nausea, vomiting, and gait ataxia.
-lesions that affect the labyrinth of the inner ear or the vestibular division of CN VIII.
