Flashcards in Lecture: The Auditory Pathway Deck (18):
In which part of the temporal bone is the internal acoustic meatus located? give some characteristics
very, very hard
IAM - facial nerve, vestibulocochlear nerve
What is the pharyngotympanic (Eustachian) tube?
Connects the middle ear to the nasopharynx
maintains equilibrium in pressure
Why is the middle ear a high risk space for infection?
the nasopharynx which is prone to infection
mastoid air cells - infection may spread to middle cranial fossa >> encephalitis
Internal jugular vein lies inferior - thrombosis risk
Internal carotid artery - pulsatile tinnitus
Nerves - chorda tympani etc - infection risk
What are the fluid filled cavities of the inner ear?
Semi-circular canals (posterior, anterior and lateral)
What kind of fluid fills these cavities in the inner ear?
- high in sodium, low in postassium
What kind of fluid is contained in the cochlear duct?
- more like intracellular fluid
- high potassium, low sodium
What are the names of the chambers created by the cochlear duct?
Scala Vestibuli - above duct
Scala Tympani - below duct
What is the name of the apex of the duct where these two chambers are continuous?
What is the entrance and exit to the cochlear called?
Entrance - Oval Window
Exit - Round Window
Between which two membranes are the cochlear hair cells located?
Tectorial Membrane - superior
Basement Membrane - inferior
Where does the vestibulocochlear nerve enter the brainstem?
At which level and via which structure does auditory information cross over the midline?
At the level of entry - cerebellopontine angle
Crosses over via Trapezoid Body
Along what route does auditory information ascend to the primary auditory cortex?
Superior Olivary Nucleus on other side (via trapezoid body)
Medial Geniculate Nucleus
Where is Heschl's Gyrus located?
Superior temporal gyrus
extends deep into the cerebral hemispheres
Give some specialisations of the auditory pathway
Bilateral - allows us to differentiate timing, loudness and therefore location
Which regions of the basilar membrane respond to which types of sound?
Apex responds to Low pitch
sound information of low pitch projects to the anterolateral part of Heschl's Gyrus
What are the secondary auditory areas and what are their functions?
motor/production of words