14 - Auditory System Flashcards
1
Q
Endolymph
A
- High K+ solution found in the scala media
- Runs in the membranous labyrinth
- +80 mV potential compared to perilymph
- Secreted by stria vascularis
2
Q
Perilymph
A
- High-sodium solution (Similar to CSF)
- Present in two cochlear compartments separated by the scala media (endolymph):
- Scala vesibuli
- Scala tympani
- Runs outside of the membranous labyrinth
3
Q
Middle ear ossicles (bones)
A
- Malleus
- Incus
- Stapes
4
Q
Human audible range
A
20-20,000 Hz (best is 3,000)
5
Q
Helicotrema
A
passage located at the end of the basilar membrane so the scala vestibuli and scala tympani can communicate
6
Q
Cochlear Root Neurons
A
- 2nd order neurons off the central projection of the cochlear nerve
- Send axons to SC for auditory startle reflex
7
Q
Olivocochlear Bundle
A
- Efferent fibers
- Run from superior olivary complex to the outer hair cells
- Origin is in the periolivary nuclei
8
Q
Dorsal Cochlear Nucleus Path
A
- Immediately decussate in the dorsal acoustic striate
- Fibers ascend in the contralateral lateral lemniscus
- Completely bypass the olivary complex
- Terminate in the inferior colliculus
9
Q
Ventral Cochlear Pathway
A
- Terminate in the ipsilateral superior olivary complex
- Fibers leave SOC to run in the ipsilateral lateral lemniscus to the inferior colliculus
- Decussate via the trapezoid body
- Terminate in the contralateral SOC
- Fibers leave SOC to run in the contralateral lemniscus to the inferior colliculus
10
Q
Conductive Hearing Loss
A
- Mechnical problem
- Middle, inner ear
- Infections, diseases cause ossicle rigidity
- Loss of conduction = simple attenuation
11
Q
Sensorineural hearing loss
A
- Damage to inner ear (hair cells, cochlear nerve, central auditory systems)
12
Q
Dorsal Acoustic Striate
A
Point of decussation of dorsal cochlear nucleus pathway
13
Q
Inferior quadrigeminal brachium
A
Path from inferior colliculus to the medial geniculate body of the thalamus
