Final Pt. 3 Flashcards
What three features make the entrance into the ear?
auricle (pinna), external auditory canal (aucoustic meatus), typanic membrane (eardrum)
What are the three ossicles/ their location?
maleus, incus, stapes, found in tympanic cavity
Purpose of the ossicles?
transmit vibratory motion of eardrum to oval window, dampened by tensor tympani and stapedius muscle
what does oval window and round window do?
OW- initiates movement of fluid to cochlea
RW- dissapates sound
What make up the inner ear (2 parts)
membranous and bony labryinth
What is the bony labyrinth?
contains vestibules, semicircular canals (involves in balance) , and cochlea
filled w/ perilymph
What system is in bony labyrinth
static vestibular system- saccule and urtricle in vestibles maintain orientation of head w/ rest of body
What is a vestible?
2 sacs of perilymph, house equilbirum maculae
What is the membranous labryinth?
membranous sacs within bony labriyth, filled with endolymph
Anatomy of semicircular canals?
membranous semicircular ducts line canals, each end has ampulla- house crista ampullaris, equilibrium receptors, respond to movements of head
What is the cochlea?
a spiral bony chamber that extends from anterior vestibule, coils around modiolus
contains cochlear duct and organ of corti
3 parts of cochlea?
scala vestibuli
scala media (cochlear duct- endolymph)
scala tympani (ends at round window)
parts of scala media (3)?
bony spiral lamina
basilar membrane
Nerve VIII runs from organ of corti to brain
High vs low pitch?
high- sounds cause deflection of basilar membrane to oval window
low- deflect away from oval window
long fibers have a…
lower pitch
how do sound vibrations cause impulses?
beat typamic membrane- pushes ossicles- presses fluid against windows- shearing force on hair cells- stim. coch nerve to send impulses
inaudible vs audible sounds?
low vs high frequency
travel around heliocotrema vs. cochlear ducts
dont excite hair cells vs. excite basilar membrane
Anatomy of organ of corti
inner/ outer hair cells
afferent fibers of cochlear nerve attach to basal hair cells
what are sterocilia?
hair cells in organ of corti, protrude into endolymph, touch tectorial mebrane
The excitation of hair cells in OOC does what?
opens mechanical ion channels, causes graded potential
Inner vs outer hair cells?
inner hair cells: sensory, nerve endings that send acoustic info
outer hair cells : amplify basilar membrane (improve hearing sensitivity)
Structures of hair cells?
attach to nerve VIII, have sterocillia, single kinocilim, linked by tiplinks
DRAW hair cell
DRAW
movement of the basilar membrane?
bending of hair cells put tension of tip links, opens K channels, causes graded depolarization- release of NT
Hair must bend towards tallest sternocillia for NT to be released
Anatomy of crista ampullara?
receptor for dynamic equilibrium (balance, movement, eye impartiality)
each crista has hair cells extending into gel called the cupula
How does crista respond to changes in velocity?
respond, result is brain informed of rotantional head movements
Anatomy of maculae?
sensory receptors for static cells, sterocillia/kinocilla in otholithic membrane
What is otholithic membrane?
jellylike mass with CaCO3 stones
horizontal movement- urtricular hairs
vertical movement- sacular hairs
What is vestibular apparatus?
equilbrium receptors in semicircular canals and vetsible
static and dynamic equilibrium
movement of head with kinocillia?
forward- towards kinocilloia (depolarize)
backwards- away kinocillia (hyperpolarize)
Auditory pathway to brain?
cochlea-spiral ganglion- cochlear nuclei- superior olivary nucelus, inferior collicus
Auditory pathway from auditory cortex?
dessucates, inferior collicus (auditory reflex center), thalamus, primary auditory cortex
