Neuro4 Flashcards
What is the structure that houses the auditory and vestibular sense organs called?
The bony labyrinth (petrous portion temporal bone)
Where is the membranous labyrinth of the Auditory System?
Inside the bony labyrinth
- of the petrous portion of the temporal bone
What type of fluid fills the inside of the membranous labyrinth?
Endolymph
What fluid lies between the bony and membranous labyrinths?
Perilymph
Is the perilymph inside the membranous labyrinth?
NO.
It is just outside the membranous portion.
What comprises the auditory apparatus within the labyrinth?
the Cochlea
What comprises the vestibular apparatus within the cochlea?
Three semicircular canals/ducts
as well as the utricle and saccule
How does sound enter the ear?
Via outer ear and external auditory meatus and Tympanic Membrane
What is the middle ear filled with?
Air and 3 small bones
What are the 3 ossicles of the middle ear called?
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)
Trace the structures involved through the inner ear beginning with the Tympanic Membrane:
Tympanic Membrane
Malleus
Incus
Stapes
(this makes up the connection between the inner and outer ear)
Is air pressure of the inner ear normally equal to atmospheric pressure?
Yes.
connected by the auditory (eustachian) tube
What connects the Stapes to the Cochlea?
The Oval Window
What are the 3 scalae (fluid filled compartments) of the inner ear?
Scala Vestibuli (superior) Scala Tympani (inferior) Scala Media (between)
Where do the scala vestibuli and the scala tympani meet?
Helicotrema
the end of the ducts
What are the scala vestibuli and scala tympani filled with?
Perilymph
What is the scala media filled with?
Endolymph
What windows open up on to the scala vestibuli and scala tympani
Scala vestibuli - Oval Window (stapes connection)
Scala tympani - Round Window
What structure houses the Organ of Corti (the sound sensing organ), and what fluid lines it?
Scala media (aka Cochlear duct) Endolymph
Trace the vibration through Cochlea, starting with stapes
Stapes > Oval window > scala vestibuli > scala tympani > Round window
What stimulates the (Basilar Membrane) hair cells of the organ of Corti?
oscillations in both the scala vestibuli and scala tympani
Why does the input to the Cochlea necessitate amplification through the ossicles?
(and amplification through concentration of sound from tympanic membrane to oval window - which is much smaller)
Fluid has a higher impedence than air
What is responsible for the transduction of mechanical vibrational energy to neural activity?
Hair cells in the cochlea
What happens when the basilar membrane moves?
Causes stereocilia to bend and change shape in relation to their FIXED tips (in tectorial membrane)
This mechanical deformation opens ion channels in the hair cells. Cation influx, generates receptor potential.
Hair cell then releases neurotransmitter > depolarizes CN VIII