Ears GT

What are the three “chambers” of the cochlea and which type of fluid is in each chamber

Scala Vestibule (top) Perilymph

Scala Media (middle) Endolymph

Scala Tympani (bottom) Perilymph

The primary difference in both fluids (perilymph and endolymph) in the ion content, so

perilymph is rich in sodium over potassium, whereas endolymph is high in potassium – allowing for strong action potentials

Which aspect of the ear (in general) will collect the soundwaves

External (outer) ear; Auricle

Which structure of the ear will separate the external ear from the middle ear?

Tympanic membrane

Which aspect of the ear will contain the ossicles?

middle ear

Which aspect of the ear will contain the neuronal structures; vestibular apparatus and cochlea?

internal (inner) ear

What is the primary function of the semicircular canal apparatus?

Balance/equilibrium

What is the primary function of the cochlea apparatus?

hearing

What is the ossicle in closest proximity to the tympanic membrane

Malleus

What is the stapes in contact with

Oval window

The muscle that will dampen the vibration of the stapes on the oval window and its innervation?

Stapedius

Facial SVE(BE)though some categorize as GSE

Paralysis to of the stapedius can lead to hyperacusis (sounds very loud that aren’t normally loud)

hyperacusis (sounds very loud that aren’t normally loud)

The muscle that will dampen the vibration by adding tension to the tympanic membrane (via malleus) and innervation?

Tensor Tympani

Trigeminal V3 SVE—though some report GSE

What is the common receptor type in the semicircular canals and the cochlear duct

Hair cells (mechanoreceptors)

Semicircular canals- ampulla-saccule, utricle (FYI only)

Cochlear duct –Organ of Corti

Which cochlear structures are comprised of perilymph

Scala Vestibuli and Scala Tympani

Endolymph is found in the

scala media

The vibration of the oval window will continue into which cochlea chamber

scala vestibuli

The Scala Vestibuli is separated from the Scala media by what structure

Vestibular membrane (Reissner’s membrane)

The area (apex) at which the scala vestibuli continues as the scali tympani?

Helicotrema

What structures is the basiliar membrane found between

Scala Media (Cochlear duct) and

Scala Tympani

Think of the basilar membrane as the

“basement” of the scala media

The gelatinous moveable membrane with hair cells embedded within it is known as the…

tectorial membrane

What is the neuronal functional aspect of the scala media (cochlear duct)

organ of corti

The scale tympani will dissipate sounds waves through which structure

round window

Waves that leave the round window are those that

have either left the scala media (cochlear duct) and/or those that never entered the scala media in the first place

Which chamber will house the organ of corti (the functional unit of the ear)

Scala media (AKA Cochlear duct)

Endolymph filled

Which cranial foramina will the vestibulocochlear nerve run through on its way to the auditory cortex (temporal)

Internal acoustic meatus

Can you tell the story of hearing from vibration to AP initiation?

Waves caused by vibrations entering via the stapes/oval window into the Scala V cause the vestibular membrane to move- and waves running through the scala tympani cause the basilar membrane to move—causing the hair cells to bend at the tectorial membrane causing AP at the cochlear aspect of the VIII nerve

What is the branch of the Basilar artery (COW) that helps perfuse the inner ear structures

Labyrinthine artery

What are the two nuclei, located at pontine-medullary junction that continue to process auditory messages on the way to the cortex

Ventral Cochlear Nucleus  (projects to Superior Olive)

Dorsal Cochlear Nucleus (projects to Inferior Colliculus)

Which structure along the pathway will help determine where sounds came from (direction)

superior olive nuclei

Which structure will help differentiate between frequencies

inferior colliculus

Which aspect of the thalamus will the auditory messages move through

Medial geniculate nucleus of thalamus (weedwacker of auditory message leaving only the important messages)

Ultimately, where does the auditory message go to interpret and result in hearing

Auditory cortex of temporal lobe