L45 Auditory neuro Flashcards
CNVIII divisions
cochlear
vestibular
Vestibule contains two elargements of membranous labyrinth
Utricle
Saccule
Perilymph
Fills
Similar to
Fills bony labyrinth
SImilar to CSF
Endolymph
FIlls
Similar to
Fills membranous labyrinth
Similar to intracellular fluid
Perilymph and endolymph are separated by
Tight junctions in hair cells
Tight junctions in hair cells cause
voltage and concentration gradients needed for transduction
Perilymph is continuous with ______ thru ______
subarachnoid space thru cochlear aqueduct
Endolymph is resorbed in
endolymphatic sac
Endolymph is produced by ____ in _____
produced by specialized cells in cochlea
Meniere’s disease
transient attacks of vertigo, nausea, hearing loss, tinnitus
Obstruction of endolymph causes
swelling of membranous labyrinth
Hair cells project into
Endolymph
Maculae stimulus
linear acceleration
Cristae stimulus
angular acceleration
Organ of Corti
Sound
Deflection toward tallest stereocilia vs away
Toward: depolarization
Away: hyperpolarization
Order of outer and middle ear
Tympanic membrane Malleus Incus Stapes Perilymph
Blocks the sound of own voice
Stapedius pulling stapes away from oval window
Stapedius innervation
VII
Blocks chewing sound
Muscle
Bone
Direction
Tensor tympani pulling malleus toward middle ear
Tensor tympani innervation
V
Scala vestibuli contains
perilymph
Scala media contains
Other name
endolymph
Cochlear duct
Scala tympani contains
perilymph
Cochlea contains
Scala vestibuli
Scala media
Scala tympani
Modiolus
What is it
Contains
Spongy bone at core of cochlea
contains spiral ganglion and cell bodies of primary afferents
Organ of corti location
Basilar membrane
Inner hair cells are stimulated by
endolymph movement
Not attached to gelatinous tectorial membrane
Outter hair Cells are stiimulated by
Vibrations in basilar membrane
Inserted into tectorial membrane
Cochlear implant
What is damaged
Where do electrodes go
Cochlea hair cells are damaged
Electrods in round window into scala tympani at different points along basilar membrane
Primary ascending auditory pathway
Consists of fibers from
Lateral lemniscus
Consists of fibers from dorsal cochlear nucleus
Primary auditory cortex location
Transverse temporal gyri of Heschl
Sound Localization
Superior Olivary nucleus
Superior olivary nucleus receives fibers from
Laterality
location
Receives fibers form bilateral cochlear nuclei
Cross midline thru trapezoid body
Superior olivary nucleus subnucleus responsible for arrival time comparison
Medial
Vestibular division role
linear and angular acceleration
posture, coordinate eye and head movementh
Crista
transversely oriented ridge with hair cells
Cupula
stereocilia in gelatinous mass
Utricle
Detects
Macula when head upright
Stereocilia
Detects forward-backward and side to side
Macula is horizontal when head upright
Stereocilia face up
Saccule
Detects
Macula when head upright
Sterocilia
Detects forward-backward and up-down
Macula is vertical when head upright
Stereocilia face laterally
Otolithic membrane
What is it
Location
Contains
Gelantinous membrane of macula
Contains calcium carbonate crystals, otoconia, otoliths
Otolithic membrane vs endolymph
Denser due to crystals
Primary afferent cell bodies
Scarpas ganglion in internal auditory canal
Scarpas peripheral process
synaptic ending on hair cells
Scarpas central process
vestibular nuclei of rostral medula, caudal pons
Vestibular inputs (5)
Semicircular duct Macula Cerebellum Spinal cord Contralateral vestibular nuclei
Lateral vestibulospinal tract
Nucleus
Area
Lateral nucleus
Lateral funiculus
Lateral vestibulospinal tract
laterality
Travels to
Purpose
Ipsilateral antigravity muscles
postural changes to accommodate tilts in body
Medial vestibulospinal tract
Nucleus
Area
Medial nucleus
extents to cervical cord via MLF
Medial vestibulospinal tract
Stabilize head movement during walking
Coordinate head and eye movement
Vestibuloocular reflex
Afferent
Efferent
Afferent: VIII
Efferent: III, IV, VI
Vestibuloocular reflex
interneuronal connections
Vestibular nuclei to MLF to III, IV, VI, and Reticular formation
Spin to left
Left semicircular duct excited
Right Semiciruclar duct hyperpolarized
Right lateral rectus contract, left inhibited
Left medial rectus contract, right inhibited
Left lateral rectus inhibited
Alcohol
Increase alcohol decreases cupula density compared to endolymph
