Anatomy/Physiology Flashcards
What is the function of the GJB2 gene?
It encodes a gap junction protein that transmits ions
The gradient across the stria vascular is is maintained by:
Na-K pumps
A 23yo w/late-onset congenital syphilis presents to clinic after a hearing test that showed b/l symmetric moderate SNHL. He reports experiencing vertigo when he was next to the stage at a rock concert the previous week. In regard to middle ear anatomy, which of the following have to be present for him to experience this phenomenon?
Tullio phenomenon - inflammatory lesions of the labyrinth (gummas) lead to labyrinthine fistulas, endolymphatic hydrops w/eventual degeneration of the membranous labyrinth. Also loss of type II hair cells in the semicircular canals and otoliths in otosyphilis.
Aminoglycoside ototoxicity is most commonly associated with damage to which ofc the following sites within the inner ear?
Outer hair cells
Aspirin and other salicylate use can cause severe tinnitus and reversible SNHL, however, it is expected to recover within __.
72hrs (3d)
Describe the acoustic reflex.
Upon exposure to a loud noise (typically w/in the 70-100dB range, there is contraction of b/l stapedius muscles, innervated by the facial nerve.
(Stapes bones are shown as a stirrup-shaped stick figure).
A patient undergoes acoustic reflex threshold testing as part of a possible retrocochlear pathology workup. A 70dB click is applied to activate the afferent limb of the reflex. The efferent limb is measured by:
Assessing changes in TM compliance - contraction of the stapedius muscle decreases the TM compliance as a protective measure.
Two types of nerve cells comprise the cochlear nerve afferents ___.
Type I (95%) and Type II (5%).
Type I cochlear nerve afferent cells are ___ and synapse directly on ___.
Type I cochlear nerve afferent cells are Bipolar and synapse directly on the body of a single Inner hair cell.
Type II cochlear nerve afferent cells are ___ and branch to synapse onto ___.
Type II cochlear nerve afferent cells are Pseudounipolar and branch to synapse onto multiple Outer hair cells..
Streptomycin and Gentamicin are known as mostly ___ agents compared to Neomycin, Amikacin, Tobramycin and Kanamycin that are primarily ___.
Streptomycin and Gentamicin are known as mostly Vestibulotoxic agents compared to Neomycin, Amikacin, Tobramycin and Kanamycin that are primarily Cochleotoxic.
An intact sound transmission mechanism (__) must be present to test for the Tullio phenomenon.
Intact TM, ossicular chain, and mobile footplate
Describe recruitment in the setting of SNHL.
Recruitment = increase in perception of loudness of sound in an ear with SNHL (damaged/ineffective hair cells “recruit” adjacent hair cells w/normal fxn., which then respond to that signal - resulting in narrowing range btwn. softest sound a person can hear and loudest sound a person can tolerate). B/c the defect is with the hair cells, recruitment is a sign of cochlear pathology.
The absence of recruitment in the setting of an ear w/sensorineural HL suggests a ___.
Retrocochlear lesion
The basic pathway for cochlear afferent fibers is:
Inner/Outer hair cells -> cochlea -> cochlear nerve -> cochlear nuclei -> superior of ovary complex -> lateral lemniscus -> inferior colliculus -> auditory cortex
A 70dB click is applied to activate the afferent limb of the acoustic reflex. The efferent limb is measured by ___.
Assessing changes in the TM compliance.
(The contraction of the stapedius muscle decreases TM compliance as a protective measure).
Patient states “she hears her footsteps loudly when she walks,” name this finding.
Autophony
-
- aural pressure
- hyperacusis
- unstable gait
- sound or pressure evoked vertigo
Vestibular manifestations of Superior SSCD include:
- autophony
- pulsatile tinnitus
- aural pressure
- hyperacusis
- unstable gait
- sound or pressure evoked vertigo
Vestibular manifestations of Superior SSCD include:
- autophony
- pulsatile tinnitus
-
-
- unstable gait
- sound or pressure evoked vertigo
Vestibular manifestations of Superior SSCD include:
- autophony
- pulsatile tinnitus
- aural pressure
- hyperacusis
- unstable gait
- sound or pressure evoked vertigo
Vestibular manifestations of Superior SSCD include:
- autophony
- pulsatile tinnitus
- aural pressure
- hyperacusis
-
-
Vestibular manifestations of Superior SSCD include:
- autophony
- pulsatile tinnitus
- aural pressure
- hyperacusis
- unstable gait
- sound or pressure evoked vertigo
Pulsatile tinnitus can occur due to ___.
Exposure of the canal to changes in CSF pressure, or to the flow of adjacent blood vessels.
Audiogram results of a patient w/SSCD:
Most commonly: symmetric hearing
Also: Conductive HL w/larger low-frequency air-bone gaps and supranormal bone conduction
Acoustic reflex testing in a patient w/SSCD:
Acoustic reflex testing is normal.
A patient with SSCD will have ___ ECOG and ___ VEMP testing results.
Elevated ECOG, SP/AP ratio >0.4.
Low threshold VEMP w/high amplitudes.
The utricle senses ___.
Linear acceleration in a horizontal plane.
The saccule senses ___.
Linear acceleration in a vertical plane.
Displacement of the ___ towards the ___ causes depolarization.
Displacement of the steriocillia towards the kinocillium causes depolarization.
In the Utricle, the kinocillia are oriented ____ the striola.
In the Saccule, the kinocillia are oriented ____ from the striola.
In the Utricle, the kinocillia are oriented TOWARD the striola.
In the Saccule, the kinocillia are oriented AWAY from the striola.
The vestibulo-ocular-reflex (VOR) senses __ movement and creates an equal and opposite ___ movement to maintain visual fixation.
The vestibulo-ocular-reflex (VOR) senses head movement and creates an equal and opposite eye movement to maintain visual fixation.
(As you move head to the right, VOR beats to the left)
If a lesion involved the structure displayed by the arrow, which of the following will be the pathophysiologic result?
Superior SCC deficit on impulse testing
(The superior vestibular n. controls function of the superior and lateral SCC, as well as the utricle).
What structure is shown at the arrow?
The superior vestibular n. is in the posterior superior quadrant
The superior vestibular n. controls function of the ___ SCCs.
The superior vestibular n. controls function of the superior and lateral SCC.
The inferior vestibular n. controls function of the ___ SCC and the ___.
Posterior SCC and Saccule.
If a lesion involved the structure displayed by the arrow, which of the following will be the pathophysiologic result?
Posterior SCC deficit on impulse testing.
Nystagmus beats towards the ___ ear, thus suggesting a lesion on the ___ side.
Nystagmus beats towards the Healthy ear, thus suggesting a lesion on the Contralateral side.
The ___ artery supplies the utricle, superior and horizontal SCC and a small portion of the saccule.
Anterior vestibular artery
The ___ supplies the majority of the saccule and a small segment of the utricle are body.
Posterior vestibular artery
What malformation describes membranous aplasia of the cochlea and saccule (pars inferior)?
Scheibe aplasia
Through what nerve pathway is the cVEMPS potential illicited?
Inferior vestibular n.
(Acoustic signal stimulates the saccule, signal is carried through the inferior vestibular n. To the vestibular nucleus, which gets transmitted to the vestibulospinal tract and on to the ipsilateral SCM).
With the Dix-Hallpike maneuver used to diagnose BPPV, the Fast phase of the nystagmus will beat upward and roll toward the ___ side.
With the Dix-Hallpike maneuver used to diagnose BPPV, the Fast phase of the nystagmus will beat Upward and roll toward the Ipsilateral side.
The bony labyrinth is a series of bony cavities w/in the petrous part of the temporal bone that is composed of:
1)
2) vestibule
3) semi-circular canals
The bony labyrinth is a series of bony cavities w/in the petrous part of the temporal bone that is composed of:
1) cochlea
2) vestibule
3) semi-circular canals
The bony labyrinth is a series of bony cavities w/in the petrous part of the temporal bone that is composed of:
1) cochlea
2)
3) semi-circular canals
The bony labyrinth is a series of bony cavities w/in the petrous part of the temporal bone that is composed of:
1) cochlea
2) vestibule
3) semi-circular canals
The bony labyrinth is a series of bony cavities w/in the petrous part of the temporal bone that is composed of:
1) cochlea
2) vestibule
3)
The bony labyrinth is a series of bony cavities w/in the petrous part of the temporal bone that is composed of:
1) cochlea
2) vestibule
3) semi-circular canals
The membranous labyrinth lies within the bony labyrinth and consists of the:
1)
2) semi-circular ducts
3) utricle and saccule
The membranous labyrinth lies within the bony labyrinth and consists of the:
1) cochlear duct
2) semi-circular ducts
3) utricle and saccule
The membranous labyrinth lies within the bony labyrinth and consists of the:
1) cochlear duct
2)
3) utricle and saccule
The membranous labyrinth lies within the bony labyrinth and consists of the:
1) cochlear duct
2) semi-circular ducts
3) utricle and saccule
The membranous labyrinth lies within the bony labyrinth and consists of the:
1) cochlear duct
2) semi-circular ducts
3)
The membranous labyrinth lies within the bony labyrinth and consists of the:
1) cochlear duct
2) semi-circular ducts
3) utricle and saccule
The bony labyrinth is lined with ___ and contains ___.
The bony labyrinth is lined with periosteum and contains perilymph.
The membranous labyrinth is filled with ___.
The membranous labyrinth is filled with endolymph.
The muscles of the upper face are under ___ cortical control, while the lower facial musculature is under ___ cortical control.
The muscles of the upper face are under bilateral cortical control, while the lower facial musculature is under contralateral cortical control.
A definitive diagnosis of Ménière’s disease according to 2020 CPG:
- ___
- Audiometric confirmation of fluctuating low-to-mid frequency SNHL in the affected ear on at least 1 occasion before, during, or after 1 of the episodes of vertigo
- At least 2 spontaneous episodes of rotational vertigo lasting 20mins - 12hrs
- Causes excluded by other tests
Fluctuating aural symptoms (tinnitus, aural fullness, HL) in affected ear
A definitive diagnosis of Ménière’s disease according to 2020 CPG:
- Fluctuating aural symptoms (tinnitus, aural fullness, HL) in affected ear
- _____
- At least 2 spontaneous episodes of rotational vertigo lasting 20mins - 12hrs
- Causes excluded by other tests
fluctuating low-to-mid frequency SNHL in the affected ear on at least 1 occasion before, during, or after 1 of the episode of vertigo