Vertigo and Motion Sickness Quiz

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Questions and Answers

What condition is characterized by nausea and vomiting due to sensory input mismatch?

Motion sickness (correct)

Labyrinth dysfunction

Vertigo

Ménière’s syndrome

Which cranial nerves are primarily responsible for eye movements?

CN I, II, VIII

CN V, VII, IX

CN III, IV, VI (correct)

CN XI, XII

What is a common symptom accompanying vertigo?

Excessive salivation

Tinnitus (correct)

Pallor

Profuse sweating

Which of the following can lead to labyrinth dysfunction?

Head injuries Signup and view all the answers

What symptom is NOT typically associated with motion sickness?

Visual impairment Signup and view all the answers

What is the primary function of the utricle in the vestibular apparatus?

Detect horizontal movement of the body Signup and view all the answers

What happens to hair cells when stereocilia bend toward the kinocilium?

They experience depolarization Signup and view all the answers

Which of the following statements regarding cochlear implants is correct?

They bypass damaged hair cells to stimulate auditory nerves Signup and view all the answers

What is the effect of bending stereocilia away from the kinocilium?

It leads to hyperpolarization of hair cells Signup and view all the answers

Which part of the vestibular apparatus is oriented in an anteroposterior plane?

Saccule Signup and view all the answers

What is the primary role of the semicircular canals?

Detect rotational movement of the head Signup and view all the answers

What is the outcome of a labyrinthectomy?

Loss of balance and coordination Signup and view all the answers

How do otolith organs contribute to equilibrium?

They respond to the pull of gravity for body position detection Signup and view all the answers

What is the role of K+ ions in the auditory system?

They help generate auditory signals. Signup and view all the answers

Which structure secretes endolymph in the auditory system?

Stria vascularis Signup and view all the answers

What initiates the depolarization of afferent neurons in the auditory pathway?

Release of glutamate from hair cells Signup and view all the answers

Where do the axons of bipolar cells from the spiral ganglion project?

Cochlear nuclei Signup and view all the answers

What is the sequence of neuron types in the auditory pathway starting from the hair cells?

First-order -> Second-order -> Third-order -> Fourth-order Signup and view all the answers

What structure is the auditory cortex located in?

Temporal lobe Signup and view all the answers

Which neurons do NOT contribute to the auditory signaling pathway?

Neurons in the nucleus of the optic tract Signup and view all the answers

Which structure acts as the final relay for auditory impulses?

Medial geniculate nucleus Signup and view all the answers

What is the primary function of the semicircular canals?

To detect angular acceleration Signup and view all the answers

What role does endolymph play in the function of the semicircular canals?

It provides inertial mass during angular acceleration Signup and view all the answers

During the beginning of rotation, what initial eye movement occurs according to the vestibuloocular reflex?

Eyes drift slowly in the opposite direction Signup and view all the answers

What happens to the eyes at the end of rotation according to the vestibuloocular reflex?

They continue to move in the direction of the previous spin Signup and view all the answers

Which structure in the brainstem forms the vestibulospinal tract?

Vestibular nucleus Signup and view all the answers

What type of sound causes fluid vibration to reach its maximum at the apex of the cochlea?

Low pitch sound Signup and view all the answers

What is the primary cause of conduction deafness?

Impaired sound transmission in the external or middle ear Signup and view all the answers

What corrective role does the cerebellum play in relation to head movements?

It monitors information and makes adjustments Signup and view all the answers

Which test distinguishes between nerve deafness and conduction deafness?

Weber test Signup and view all the answers

Which type of receptors are involved in monitoring the body's position and movements?

Vestibular receptors Signup and view all the answers

Which area of the brain receives impulses for maintaining equilibrium and coordinating movements?

Cerebellum Signup and view all the answers

In the Rinne test, what observation indicates conduction deafness?

Vibrations in air are not heard after bone conduction Signup and view all the answers

What typically causes nerve deafness?

Damage to the cochlea or auditory pathway Signup and view all the answers

What does the audiogram from a pure tone audiometer represent?

Hearing thresholds at various intensities Signup and view all the answers

Which of the following conditions can lead to conduction deafness?

Otosclerosis Signup and view all the answers

Which area of the auditory cortex processes impulses from high pitch sounds?

Posteromedial region Signup and view all the answers

What is the primary function of the auricle (pinna)?

Collect and direct sound to the ear canal Signup and view all the answers

Which part of the ear is responsible for detecting movements of the head?

Semicircular canals Signup and view all the answers

What is the role of the auditory ossicles in the middle ear?

Amplify sound waves and transmit them to the inner ear Signup and view all the answers

What distinguishes conduction deafness from nerve deafness?

Conduction deafness involves the outer or middle ear, nerve deafness involves the inner ear or auditory nerves. Signup and view all the answers

What is the function of hair cells in the cochlea?

Convert sound waves into neural signals Signup and view all the answers

What role does the tympanic membrane play in hearing?

It vibrates in response to sound waves Signup and view all the answers

Which structure is primarily responsible for converting sound waves into neural signals?

Cochlea Signup and view all the answers

What are the fluid-filled chambers in the inner ear primarily associated with?

Balance and equilibrium Signup and view all the answers

Which of the following best explains air conduction?

Transmission of sound through the outer ear to the inner ear Signup and view all the answers

What is the primary purpose of the impedance matching device in the middle ear?

To adapt sound waves to the inner ear fluid environment Signup and view all the answers

Study Notes

Hearing & Equilibrium

Hearing: The process of detecting sound
Equilibrium: The sense of balance
External ear: The outer part of the ear; includes the pinna and ear canal
- Pinna: Collects and funnels sound waves
- Ear canal: Amplifies sound waves
Middle ear: The cavity between the eardrum and inner ear
- Tympanic membrane (eardrum): Vibrates in response to sound waves
- Auditory ossicles (malleus, incus, stapes): Amplify and transmit vibrations
Inner ear: Fluid-filled chambers containing the structures for hearing and balance
- Cochlea: Organ of hearing; contains receptor cells (hair cells)
  - Basilar membrane: Vibrates in response to fluid waves
- Vestibular system: Responsible for maintaining balance
  - Semicircular canals: Detect head rotation
  - Otolith organs (utricle and saccule): Detect head position and linear movement

Learning Outcomes for Hearing

Explain factors affecting sound pitch and loudness
Explain the transmission of sound through the auditory system
Describe the transmission of impulses in the auditory pathway
Define air and bone conduction of sound
Differentiate between conduction and nerve deafness

Impedance Matching

Auditory ossicles (malleus, incus, stapes): Act as a lever system to transfer sound waves to the oval window
The ossicular lever system increases the force transmitted substantially
The tympanic membrane surface area is larger than the oval window surface area
Combining these two factors increases the pressure exerted on the cochlear fluid, exceeding the increase in pressure across the middle ear approximately 20 times.

Other Structures in the Middle Ear

Skeletal muscles (tensor tympani and stapedius): Involved in the tympanic reflex to protect auditory receptors
Round window: Dissipates the sound waves
Eustachian tube: Equalizes pressure inside the middle ear with atmospheric pressure

Tympanic Reflex

Trigger: Very loud sound
Action: Tensor tympani muscles contract, pulling the malleus inward
Action: Stapedius muscles contract, pulling the stapes outward and away from the oval window
Purpose: Protects auditory receptors from excessive stimulation

Inner Ear: Cochlea

Space between bony and membranous labyrinths Contains perilymph (rich in Na+ ions)
Scala media: Contains endolymph (rich in K+ ions)
Endolymph has a higher K+ concentration compared to perilymph or fluids outside of the inner ear

Endolymph

High K+ plays a role in generating auditory signals
Low Na+
Secreted by stria vascularis
Endolymph is high in K+

Auditory Receptors: Hair Cells

Bending of stereocilia towards kinocilia depolarizes the hair cells; toward away hyperpolarizes the hair cells
Receptor potential leads to neurotransmitter release (glutamate)
Depolarization leads to neurotransmitter release (glutamate); leads to depolarization of afferent neurons

Sound Transmission

Sound waves strike the tympanic membrane, which vibrates
Vibration transfers energy to the auditory ossicles
Stapes vibrations against oval window creates fluid waves in the cochlea
Fluid waves cause hair cells to bend and generate electrical signals
Signals transferred to the brain via the vestibulocochlear nerve

Auditory Pathway

Bipolar cells in the spiral ganglion
Cochlear nuclei in the medulla; then cross to the contralateral side of the brainstem
Third order neurons
Inferior colliculus
Fourth order neurons
Medial geniculate nucleus.
Fifth order neurons
Auditory cortex in the temporal lobe.

Conduction of Sound

Ossicular/air conduction: Sound waves conducted to the inner ear via the tympanic membrane and auditory ossicles. Main pathway for normal hearing
Bone conduction: Transmission of vibrations from the skull to the fluid of the inner ear

Sound Waves

Loudness: Related to amplitude; higher amplitude, louder sound
Pitch: Related to frequency; higher frequency, higher pitch
- Frequency range: 20-20,000 Hz audible to humans
- Best pitch discrimination: 1000-4000 Hz

Anatomy of the Cochlea

Spiral-shaped organ
Basilar membrane: Narrower, thicker at the base, wider and thinner at the apex, tailored to different frequencies
High frequencies stimulate hair cells at the base; low frequencies stimulate hair cells at the apex

Different Frequencies Stimulate Hair Cells

20,000 Hz (High frequency)
1,500 Hz (Medium frequency)
20 Hz (Low frequency)
- Different frequencies stimulate hair cells at different locations along the basilar membrane

Determination of Loudness

Loudness: Determined by amplitude
Frequency of action potentials in single auditory nerve fibers is proportional to loudness
Vibration of basilar membrane and recruitment of hair cells determines loudness
High frequency of action potentials in auditory nerves correspond to loudness

Determination of Pitch

Pitch: Determined by frequency
Higher frequency, higher pitch
Frequency affects loudness
Audible frequency range for humans: 20-20,000 Hz
Best pitch discrimination: 1000-4000 Hz

The Auditory Pathway

Anterior auditory pathway to prefrontal cortex
Posterior auditory pathway to posterior parietal cortex
Primary auditory cortex
Secondary auditory cortex
- Auditory association cortex

Thresholds of hearing

Threshold of hearing: 0 dB (Sound intensity = Standard sound)
Threshold of pain: ~120 dB

Hearing Loss (Deafness)

Conduction deafness: Impaired sound transmission in external or middle ear (obstructions or damage to ossicles)
Nerve deafness: Degeneration of hair cells (chronic exposure to loud noise, aging, damage to the auditory pathway, or tumors)

Audiometry

Pure tone audiometer: Provides standard tones of different pitches and variable intensity
Used to determine hearing threshold at various frequencies

Weber & Rinne Tests

Weber: Tuning fork placed on head, used to diagnose issues in bone conduction
Rinne: Tuning fork placed on mastoid process and then near ear; used to differentiate between conduction and sensorineural loss

Cochlear Implants

Used in sensorineural hearing loss
Bypasses damaged hair cells and directly stimulates auditory nerve fibers
- Sounds are converted to electrical signals for stimulation through the auditory nerve fibers

Equilibrium (Balance)

Learning Outcomes: Functions of utricle and saccule; Function of semicircular canals; Effects of labyrinthectomy
Utricle: Detects horizontal movement
Saccule: Detects vertical movement
Semicircular canals: Detect angular acceleration/deceleration
Labyrinthectomy: Removal of inner ear; can impair balance

Otolith Organs

Detect position of head to gravity (static equilibrium) - Pulling of gravity on otoliths triggers tonic discharge in the macula
Detect linear movement of the head (dynamic equilibrium)
- Utricle (horizontal movement); Saccule (vertical movement)

Semicircular Canals

Detect angular/rotational acceleration and deceleration
Endolymph contributes inertial mass to the canal's response to movement

Vestibulo-ocular Reflex (VOR)

Initiated by impulses from semicircular canals
Compensates for head movements to allow eyes to remain fixed on a stationary point
At beginning of rotation, eyes drift in the opposite direction then rapidly move back toward movement

Vestibular Nucleus

Vestibulospinal tract: Regulates muscle tone in response to head movement
Impulses to the neck muscles and extraocular muscles that provide eye fixation and equilibrium
Impulses to the cerebellum to monitor information, make corrective adjustments, and maintain equilibrium

Input & Output of the Vestibular System

Vestibular receptors, visual receptors, and somatic receptors (skin, muscles, joints) transmit information to the cerebellum
Cerebellum processes information, makes corrective adjustments, and sends impulses to the vestibular nuclear complex
Vestibular nuclear complex relays impulses to cranial nerves III, IV, VI, and XI to control eye movements, neck, and skeletal muscles in limbs, trunk, and body to maintain equilibrium

Motion Sickness

Warning signals (nausea, vomiting, excessive salivation) precede from sensory mismatch
Simultaneous multiplanar angular accelerations, a mismatch between visual and vestibular stimuli

Labyrinth Dysfunction

Vertigo: Sensation of movement of the external environment or the head; occurs from lesions to vestibular pathways like cerebellum and brain stem
Ménière's syndrome: Characterized by recurrent vertigo with tinnitus and progressive nerve deafness; usually comes from swelling in inner ear canals

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Description

Test your knowledge on vertigo and motion sickness with this quiz. Explore the conditions, cranial nerves involved in eye movements, and symptoms of labyrinth dysfunction. Understand what typically accompanies vertigo and what is not associated with motion sickness.