Auditory System Flashcards
What are the main components of the external ear?
Auricle (pinna), external acoustic meatus, tympanic membrane
The external ear consists of structures that collect sound waves and direct them into the ear canal.
What structures are found in the middle ear?
Auditory ossicles: malleus, incus, stapes, oval window
These bones transmit sound vibrations from the tympanic membrane to the inner ear.
What are the two parts of the inner ear?
Cochlea, vestibular labyrinth
The inner ear is responsible for hearing and balance.
What does the bony labyrinth contain?
Perilymph
The bony labyrinth is the outer structure of the inner ear.
What does the membranous labyrinth contain?
Endolymph
The membranous labyrinth is involved in auditory and vestibular functions.
What is the function of the labyrinthine artery?
Supplies blood to the inner ear
It is a branch of the anterior inferior cerebellar artery (AICA).
What is the shape of the cochlea?
Snail-like spiral shape with a 2.5 turn
This unique shape is essential for its function in hearing.
What are the three scalae of the cochlea?
- Scala vestibuli
- Scala media (cochlear duct)
- Scala tympani
These compartments are crucial for sound transduction.
What is the role of the oval window in the cochlea?
Transmits vibrations from the stapes to the perilymph
The oval window is a membrane-covered opening that leads from the middle ear to the inner ear.
What is the modiolus?
Central bony core of cochlea containing spiral ganglion
It plays a role in the auditory nerve pathway.
What is the function of the helicotrema?
Connects scala vestibuli and scala tympani
It allows fluid communication between these two scalae.
What separates the cochlear duct from the scala vestibuli?
Vestibular membrane (Reissner membrane)
This membrane helps maintain the distinct environments of the scalae.
What separates the cochlear duct from the scala tympani?
Basilar membrane
The basilar membrane plays a crucial role in sound transduction.
What is the organ of Corti?
Spiral organ containing hair cells
It is the sensory organ responsible for converting sound vibrations into neural signals.
What stimulates the hair cells in the organ of Corti?
Vibration of tectorial membrane against the stereocilia
This process is essential for auditory perception.
True or False: The inner hair cells are part of the organ of Corti.
True
Inner hair cells are critical for transducing sound stimuli.
Fill in the blank: The auditory tube is also known as the _______.
Eustachian tube
It helps equalize pressure in the middle ear.
What is the role of the vestibular labyrinth?
Provides information for balance and maintains equilibrium
It is crucial for spatial orientation and balance.
What sends the cochlear afferent fibers?
Spiral ganglion
It consists of peripheral processes and gives the central processes as cochlear nerve (part of CN VIII)
At what junction does CN VIII enter the brainstem?
Pontomedullary junction
What is the role of the medial superior olivary nucleus?
Localizing the direction of sound
Where are the cochlear nuclei located?
At medulla level
What are the two types of cochlear nuclei?
- Dorsal (posterior) cochlear nucleus
- Ventral (anterior) cochlear nucleus
What type of neurons are the first order neurons in the auditory pathway?
Bipolar cells (or Spiral ganglion)
What are the primary auditory cortex Brodmann areas?
BA 41, 42
What structure projects to the primary auditory cortex?
Medial geniculate nuclei (MG)
What is the pathway from the auditory cortex to the auditory association cortex?
Via arcuate fasciculus
What is the function of the acoustic reflex?
to protect the inner ear from damage caused by loud sounds
Fill in the blank: The auditory pathway includes the ________.
Organ of Corti
What is the role of descending auditory pathways?
sends signals from the brain back to the ear and other lower centers. It plays important modulatory and protective roles in hearing.
What do periolivary nuclei send back to hair cells in the organ of Corti?
Olivocochlear bundle (OCB)
What effect does the auditory system have to filter out noise?
Cocktail-party effect
Which nucleus projects to the nucleus of the trapezoid body?
Superior olivary nucleus
What are the components of the central auditory pathway?
- Cochlear nuclei
- Superior olivary nuclei
- Nuclei of inferior colliculus
- Medial geniculate nuclei
True or False: The cochlear nerve is part of the trigeminal nerve.
False
What are the three types of hearing loss?
- Conductive
- Sensorineural
- Central
Conductive hearing loss is due to obstruction, sensorineural is due to nerve issues, and central involves damage to auditory pathways.
What causes conductive hearing loss?
Obstruction by cerumen and otosclerosis
Otosclerosis involves progressive ossification of the ligament around the stapes.
What is sensorineural hearing loss?
Nerve deafness due to damage to the inner ear or cochlear nerve
It often includes conditions like presbycusis, which is age-related hearing loss.
What is presbycusis?
Decrease of hearing in old age from degeneration of the organ of Corti
It is a common form of sensorineural hearing loss.
What do the Rinne and Weber tests assess?
Air conduction and bone conduction
They help differentiate between conductive and sensorineural hearing loss.
What is the function of the vestibular system?
Balance and spatial orientation
It includes components like the semicircular canals and otolith organs.
Where are the receptors for the vestibular system located?
In the ampulla of semicircular canals and the otolith organs (saccule and utricle)
These receptors respond to movements and shifts in position.
What are the two types of hair cells in the vestibular system?
Stereocilia and kinocilia
They respond to bending caused by fluid movement.
What do the saccule and utricle respond to?
Linear acceleration and head tilting
They detect vertical and horizontal movements.
Fill in the blank: The Rinne test uses a _______ tuning fork.
512 Hz
This frequency is commonly used to test hearing.
True or False: Unilateral hearing deficit can occur with lesions at only one-sided cochlear nuclei.
True
This can lead to hearing loss on the affected side.
What is the role of the crista ampullaris?
It is involved in detecting rotational movements of the head
Located in the ampulla of the semicircular canals, it plays a crucial role in balance.
What are otolith organs responsible for?
Detecting linear acceleration and gravitational forces
They help the body understand its position in relation to gravity.
What are the main vestibular receptor organs?
- Semicircular canals
- Utricle
- Saccule
- Macula utriculi
- Macula sacculi
- Crista ampullaris
These structures are essential for detecting changes in head position and movement.
What type of acceleration do the semicircular canals detect?
Angular (rotational) acceleration
The semicircular canals are sensitive to head rotation, providing information on the direction and speed of head movement.
Which semicircular canals are responsible for vertical acceleration?
- Superior semicircular canal
- Posterior semicircular canal
These canals respond to movements in the vertical plane.
How does the direction of endolymph flow affect neural signals?
It results in stimulation or inhibition of neural signals
The flow of endolymph within the semicircular canals is critical for the vestibular system’s response to motion.
What are the primary and secondary vestibulocerebellar fibers responsible for?
- Primary fibers: Direct connection to cerebellar cortex
- Secondary fibers: Indirect connection to fastigial nucleus in the flocculonodular lobe
These pathways play a crucial role in balance and coordination.
What functions are maintained by the vestibular system?
- Posture
- Balance
- Coordination of eyes and head movements
The vestibular system integrates sensory information to maintain stability.
What is the role of the vestibular nerve?
Carries signals from vestibular receptors to the brain
The vestibular nerve is part of cranial nerve VIII and transmits sensory information related to balance.
What do the medial and lateral vestibulospinal tracts control?
- Medial vestibulospinal tract: Neck muscles (head movement)
- Lateral vestibulospinal tract: Motor neurons for extensor muscles (upright posture)
These tracts help in coordinating postural adjustments and head movements.
Fill in the blank: The vestibular pathway includes the vestibular receptor organs, vestibular ganglion, ________, and vestibular nuclei.
vestibular nerve (part of CN VIII)
This pathway is essential for processing vestibular information.
True or False: The vestibular system is not involved in coordinating eye movements.
False
The vestibular system plays a critical role in coordinating eye movements to stabilize vision during head motion.
What is the role of the medial longitudinal fasciculus (MLF) in the vestibular system?
Coordinates eye movement and head movement
The MLF connects various nuclei that are involved in controlling eye and neck muscle activity.
What part of the brain does the vestibular pathway relay information to?
Thalamus and cerebral cortex
This relay is important for spatial orientation and awareness.
What is the vestibulo-ocular reflex (VOR)?
A reflex that stabilizes gaze during head movements by coordinating eye movements with head motion.
It helps maintain clear vision while the head is in motion.
What are the types of nystagmus?
- Optokinetic nystagmus
- End-gaze nystagmus
- Physiological nystagmus
Nystagmus is characterized by involuntary eye movements that can occur in various forms.
What is the caloric test used for?
To assess vestibular function by inducing nystagmus through temperature changes in the ear canal.
Cold water (30°C) typically causes nystagmus in the opposite direction, while warm water (44°C) causes it in the same direction.
What does COWS stand for in the context of the caloric test?
Cold Opposite, Warm Same
This mnemonic helps remember the direction of nystagmus induced by temperature changes.
What is vertigo?
Sensation of irregular spinning movement of the patient or environment.
It is a common symptom of vestibular disorders.
Define dizziness.
A non-specific term for spatial disorientation, lightheadedness, or increased unsteadiness.
Dizziness can be a symptom of various vestibular disorders.
What is unsteadiness in vestibular disorders?
Feeling imbalanced, especially when walking.
It can be accompanied by other symptoms such as nausea and vomiting.
What is benign paroxysmal positional vertigo (BPPV)?
A vestibular disorder triggered by changes in specific head positions due to displacement of otoliths in semicircular canals.
Symptoms include dizziness, vertigo, unsteadiness, nausea, vomiting, and nystagmus.
What causes vestibular neuritis or labyrinthitis?
Inflammation of the vestibular nerve or labyrinth due to infection.
Symptoms include nausea, vomiting, dizziness, and nystagmus.
What is Ménière’s disease?
A condition characterized by increased pressure of endolymph in the inner ear.
Symptoms include episodes of vertigo, tinnitus, hearing loss, nausea, vomiting, and nystagmus.
