Chapter 10 Flashcards
(39 cards)
What are the 3 fluid-filled cochlear chambers, and the membranes that separate them
Scala vestibuli
Tectorial membrane
Scala media
Basilar membrane
Scala tympani
Which cochlear chambers have perilymph and which has endolymph
Perilymph - SV & ST
Endolymph - SM
What is the significance of ionic differences in perilymph and endolymph
SV & ST have more sodium and potassium
SM has more potassium
Different amount of ions are ready to transmit across membranes
What characteristics of the basilar membrane cause it to move differently for different frequencies?
Graded thickness, stiffness, and width - meaning it changes along the length of the BM
Base of BM sits at the oval window - narrow, thick, stiff which allows it to interpret high frequency sounds
Apex (helicotrema) - wide, thin, and flexible which allows it to interpret low frequency sounds
TONOTOPIC ARRANGEMENT
What is the function of the organ of Corti
Sensory receptor converting hydraulic to AP
Chief site for transduction of auditory inputs
What types of cells are found in the organ of Corti?
Inner and outer hair cells
Covered by tectorial membrane - moves and triggers displacement of hair cells
Principal auditory receptors=inner hair cells
Hair cells, stereocilia, mechanotransduction
See #4 structure of handout
Auditory nerve
Fibers of 8th CN
Begin at spiral ganglion in cochlea
End at cochlea nucleus on the brain stem
Cell bodies are in the modiolus?
Central auditory pathway
Cochlear nucleus
Superior Olivary complex
Inferior colliculus
Medial geniculate body
Auditory cortical areas
Characteristics of Cochlear nucleus
First relay station
Interprets frequency, intensity, and timing of sounds
First location fibers cross midline and to to contralateral side from the CN
2 divisions:
Dorsal cochlear nuclei
Ventral cochlear nuclei
Characteristics of superior olivary nuclei
Second relay station of CAP
On the pons
Interprets sound localization - primary function
Receives input from ipsilateral and contralateral cochlear nucleus
Characteristics of lateral lemniscus
Helps maintain timing and spectral information from stimulus
That is traveling along pathway
Characteristics of inferior colliculi
3rd stop in relay station
Location: on the midbrain
Purpose: integrate auditory input from all previous areas in chain
Characteristics of medial geniculate body
Last relay station
Located: thalamus
Fibers go to auditory cortex from here
Interprets intensity, frequency, auditory space
How do the functions of the dorsal and ventral regions of the MGB differ
Dorsal - sending info to association areas, interprets complex info, speech and language processing
Ventral - maintains tonotopic and sends info to primary auditory cortex. Timing and frequency
Functions are different because of there their fibers are going
Primary Auditory Cortex
Location: transverse temporal gyri of Heschl - Heschl’s gyri
Tonotopically arranged. High pitch: anterior, low pitch: posterior
Once it processes the sound the interpretation goes to the next step which is Wernicke’s
What is the relationship of Wernicke’s area and the primary auditory cortex?
Primary auditory cortex is funneling information to Wernicke’s for language comprehension. Damage to Wernicke’s means sound is trying to get there but it can’t so no language is comperehended
What is the vestibular system
Helps maintain balance and upright posture.
Provides proprioception information
Maintains equilibrium
What sources of information are used to maintain equilibrium
Visual and vestibular
what are the two chief sensory elements of the vestibular system
Semicircular canals
Otolith organs
What are the otolith organs?
Two enlargements found inside the vestibule of the bony labyrinth
Utricle & saccule - filled with endolymph
Utricle and saccule characteristics
Contain a sensory epithelium called maculae which contains hair cells
Tips of hair cells embedded in otolithic membrane
