The Auditory and Vestibular Nervous System Flashcards
How many pairs of spinal nerves are there?
31
What are the components of the PNS?
Cranial nerves
Spinal nerves
What is rostral to caudal?
Head to tail
Where does the olfactory nerve sit?
In the anterior cranial fossae by the cribriform plate.
Where does the facial nerve exit the skull?
Through the internal acoustic meatus.
Where does the glossopharyngeal nerve exit the skull?
Through the jugular foramen
Where does the vagus nerve exit the skull?
Through the jugular foramen.
Where does the accessory nerve exit the skull?
Jugular foramen
What is the function of the auricle of the ear?
Funnel the vibrations into the external acoustic meatus.
What is the external auditory meatus?
A curved tube that leads from the auricle to the tympanic membrane.
Where are auditory ossicles?
The middle ear.
What is the function of auditory ossicles?
Transmit the vibrations of the tympanic membrane to the oval window.
What are the three auditory ossicles?
Malleus
Incus
Stapes
Where is the pharyngeal opening of the pharyngotympanic (eustachian) tube?
Nasopharynx
What makes up the inner ear?
Membranous labyrinth
Bony labyrinth
What makes up the bony labyrinth of the ear?
the semi-circular canals
the vestibule
the cochlea
What is inside the bony labyrinth?
Filled with a clear fluid, the perilymph, in which is suspended the membranous labyrinth
Where is the membranous labyrinth located?
Within the bony labyrinth of the inner ear.
What is the membranous labyrinth filled with?
Endolymph
What does the membranous labyrinth consist of?
Three semicircular ducts
The utricle
The saccule
The Duct of the cochlea
What is the function of the external ear?
Collects the sound waves and channels them inward.
Also protects the tympanic membrane.
What is the function of the middle ear?
Conveys the sound vibration to the middle oval window.
What is the function of the internal ear?
Houses receptors or hearing and equilibrium.
What is the auricle of the ear?
Plate of elastic cartilage that collects the air vibration and channels them to the middle ear.
What epithelial cells line the tympanic membrane?
Simple cuboidal epithelium
What gland secretes earwax?
Ceruminous glands
Where is the middle ear located?
Within the petrous part of the temporal bone.
What does the middle ear contain, and what is it’s function?
Contains the auditory ossicles, whose function is to transmit the vibrations of the tympanic membrane to the perilymph of the internal ear.
Which auditory aussicle attaches to the oval window of the ear?
Stapes
What auditory aussicle attaches to the tympanic membrane?
Malleus
What does the tensor tympani do?
Limits movement and increases tension of the eardrum to prevent damage to the inner ear from loud noises.
What innervates the tensor tympani?
Mandibular branch of the trigeminal nerve
What does the stapedius muscle do?
Limits the vibration of the stapes due to loud noises, protecting the oval window, and decreasing the sensitivity of hearing.
What is the stapedius muscle innervated by?
The facial nerve
What is the function of the pharyngotympanic tube?
Regulates pressure within the ear.
What makes up the inner ear?
Membranous labyrinth
Bony labyrinth
Where are the sensory receptors for balance located?
Macula of utricle
Macula of saccule
Crista (in the semi-circular canals)
What does the macula utricle respond to the in ear?
Changes in acceleration/deceleration in the horizontal direction.
What does the macula saccule of the ear respond to?
Changes in acceleration in the vertical direction.
What do the crista of the ear respond to regarding balance?
Movement in any direction due to the semicircular
ducts being arranged at right angles to each other so that all three planes are represented.
How is balance detected in the ear?
The endolymph in the membranous labyrinth changes it speed of movement relative to that of the walls and is detected by the sensory receptors.
Explain how vibrations in the air are transported to the round window of the ear.
- The air vibrations move in through the external acoustic meatus, and hit the tympanic membrane.
- The tympanic membrane then moves with the vibrations.
- The vibrations are translated across to the oval window by the aussicles.
- The vibrations then enter the perilymph of the scala vestibuli.
- The vibrations then move around the cochlea of the ear in the perilymph to the helicotrema and then continue to the round window.
What do the malleus incus and stapes do?
Translate the movement of the tympanic membrane to the oval window.
What is the effect of the vibrations moving through the perilymph of the bony labyrinth.
They distort the membranous labyrinth. This distortion is detected by the spiral organ and converted into an action potential.
What innervates the cochlear portion of the ear?
The cochlear branch of the vestibulocochlear nerve.
What is contained within the internal acoustic meatus?
Vestibulocochlear nerve
Facial nerve
Where do the cochlear nuclei synapse in the brain?
The superior olivary nuclei
What do the superior olivary nuclei detect?
Localise the sound in acoustic space, and time the arrival and intensity of sound in each ear.
Explain where the impulses from the cochlear branch of the vestibulocochlear nerve initially end up.
Superior olivary nucleus
Inferior colliculus
How does the action potential travel from the vestibulocochlear nerve to the inferior colliculus?
The cochlear nuclei decussate in the medulla and then travel up the lateral lemniscus to the inferior colliculus.
Where do the action potentials travel from the superior olivary nuclei and inferior colliculus?
The action potentials travel to the medial geniculate nucleus in the thalamus which in turn send the action potential to the primary auditory cortex of the cerebrum.
Where is the superior olivary nuclei?
The pons
Where is the inferior colliculus?
The midbrain
Where in the thalamus is responsible for hearing?
Medial geniculate nucleus
What do dorsal neurons in the brain detect?
Low frequencies
What do ventral neurons in the brain detect?
High frequencies
What is Wernicke’s area in the brain responsible for?
Interpretation of spoken word
