Exam IV-Auditory Flashcards
What type of fluid FILLS the membraneous labyrinth? What type of fluid is between the bony and membranous labyrinth?
Endolymph fillls, perilymph between
How many turns for the Cochlea?
2.5
What is the point where the Scala Tympani and the Scala Vestibuli meet?
HelicoTrema
Which Scala is Superior? Which is Inferior?
SUPERIOR=Scala Vestibuli INFERIOR=Scala Tympani
Which structure houses the endolymph?
The Scala Media
Which structure contains the perilymph?
Both the Scala Vestibuli and the Scala Tympani
Where are the hair cells contained?
The Organ of Corti
What type of channels open when the stereocillia move? What is created?
Ion channels open in the hair cells, creating a receptor potential
What is released once the receptor potential is large enough?
A nerotransmitter is released causing VIII to depolarize
How many outer cells are in the organ of Corti? Inner?
3 outer cells, 1 inner
Which hair cell is large and round? Inner or outer?
Inner cells are larger and rounder. Outercells are small and thin
Which part of the cochlea senses HIGH pitch?
The base of the cochlea, so the Apex senses Low pitch
What is the central hearing pathway? What does each mean?
8-C-SLIMA 8:CN VIII….C:Cochlear Nucleus…S:Superior Olivary Nucleus….L:Lateral Lemniscus….I:Inferior Colliculus….M:Medial Geniculate Nucleus….A:Auditory Cortex
Where is the cochlear nucleus?
the medulla
what percentage of axons of the cochlear nuclei decussate in the lower pons?
80%
How do the neurons get from the medial geniculate to the primary auditory cortex?
The internal capsule
What is the hearing gyrus in the primary auditory cortex? What brodmann numbers?
Transverse gyri of Heschel, brodmanns 41 and 42
Where does the pathway split to orient eyes and head toward a sound?
At the inferior colliculus->to the superior colliculus
Where does the pathway split to wake you up with loud noises?
From the Cochlear Nuclei to the RETICULAR formation!
What pathway INHIBITS extra noise?
Descending pathway/centrfugal Pathway
How does the descending /centrifugal pathway reach the cochlea?
The internal auditory canal
What ossicle does the tensor tympani insert into? What CN innervates it?
Malleus, V
What innervates the stapedeus muscle?
VII
What is mechanical interruption of hearing? What are three examples?
Conductive Deafness: Obsrtuction, OtoSclerosis, Otitis Media
What causes Sensorineural Deafness?
disease of the nerves VIII or pathways…Toxins, drugs, infection
What is Meniere’s Disease?
Overproduction of endolymph/can’t absorb it
Would a lesion to 8CSLIMA cause total deafness?
Nope, c/o decussation at the lower pons
