Hearing and Balance (Quiz 3) Flashcards
Within the bony labyrinth of the inner ear, specialized mechanoreceptors (hair cells) are found within a membranous tube (labyrinth). What are the ducts within their bony surroundings?
1) cochlea duct within cochlea
2) semicircular duct within each canal
3) utricle and saccule within vestibule
Bony labyrinth has perilymph which is continuous with….
CSF
Membranous ducts are filled with which type of lymph?
endolymph (has high conc. of K+)
What are the smallest bones in the body?
auditory ossicles
What is known as the eardrum?
tympanic membrane
What cavity in the ear is known as the middle ear?
tympanic cavity
What is the round window in contact with?
the cochlea
What is A?
semicircular canal
What is B?
semicircular ducts
What is C?
vestibule
What is D?
ampullae
What is E?
maculae
What is F?
utricle
What is G?
saccule
What is H?
vestibular duct
What is I?
cochlear duct
What is J?
tympanic duct
What is K?
organ of corti
What is L?
cochlea
What are the swellings at the end of ducts called?
ampullae
What is the membrane for gravity called?
maculae
What are the 3 ducts in the cochlea?
1) vestibular
2) cochlear
3) tympanic duct
Within the coils of the cochlea lie spiral ganglion, they contain the cell bodies of auditory primary afferents. The organ of corti/spinal organ is a strip of neurons (hair cells) and supporting cells that rest on the ___________ membrane
basilar
What is the “receptor” in the ear?
inner hair cells
The _________________ are the ones that are displaced when endolymph moves after sound waves are transduced
inner hair cells
Sound waves arrive at which membrane?
tympanic membrane
Sound waves arrive at. the tympanic membrane. Movement of the tympanic membrane causes displacement of what?
the auditory ossicles
Sound waves arrive at. the tympanic membrane. Movement of the tympanic membrane causes displacement of the auditory ossicles. Movement of the ___________ at the oval window establishes pressure waves in the perilymph of the vestibular duct
stapes
Sound waves arrive at. the tympanic membrane. Movement of the tympanic membrane causes displacement of the auditory ossicles. Movement of the stapes at the oval window establishes pressure waves in the perilymph of the vestibular duct. The pressure waves distort the ___________ membrane on their way to the round window of the tympanic duct. Vibration o the basilar membrane causes vibration of hair cells against the ______________ membrane. Info about the region and the intensity of stimulation is relayed to the CNS over the cochlear branch of cranial nerve VIII
basilar, tectorial
The ossicular lever system reduces the distance of movement but increases the _________ of movement about 1.3x
force
What are the 2 parts of the basilar membrane?
apex and base
What does the entire basilar membrane respond to?
intense low frequency sounds
note: higher frequency sounds move from apex to base of the basilar membrane
The tuning of the ____________ membrane is the start of the tonotopic organization/map
test q
basilar
A single inner hair cell synapses on ______ afferents
10
outer hair cells are ____________
amplifiers/modifiers
What makes up the organ of corti?
-tectorial and basilar membranes
-inner and outer hair cells
Auditory primary afferents com from which hair cells?
inner hair cells
For the auditory pathway, the axons enter the brainstem at the pontomedullary junction. Each nerve sends a branch to which 2 nuclei?
1) dorsal cochlear nucleus
2) ventral cochlear nucleus
note: these cover the dorsal and lateral side of the inferior cerebellar peduncle and are located as lateral as you can go by the special sensory nuclei
At the dorsal cochlear nucleus and ventral cochlear nucleus, all the fibers synapse and 2nd order neurons pass mainly to the opposite side of the brain stem (at the trapezoid body) to terminate in the….
superior olivary nucleus
At the dorsal cochlear nucleus and ventral cochlear nucleus, all the fibers synapse and 2nd order neurons pass mainly to the opposite side of the brain stem to terminate in the superior olivary nucleus. From here, the auditory pathway passes upward through the….
lateral lemniscus
(some of the fibers terminate in the nucleus of the lateral lemniscus, bit many fibers bypass this nucleus and travel on to the inferior colliculus, where all or almost all the auditory fibers synapse)
In the auditory pathway, the 3rd order axons project to the _______________________, where all the fibers synapse
medial geniculate nucleus
(finally, the pathway proceeds via auditory radiation to the auditory cortex, located mainly in the superior gyrus of the temporal lobe)
T/F: many fibers that leave the ventral cochlear nucleus ascend but terminate in the superior olivary nucleus. A sound coming from the left reaches the left ear before the right AND a sound coming from the left will be more intense on the left as the head shadows the right ear
true
Which CN innervates the stapedius- small muscle in the middle ear involved in sound transduction and amplification?
CN VII
The ______________________ is the sensory organ for detecting sensations of equilibrium. It is encased within the bony labyrinth. Within this is the membraneous labyrinth- the function part
vestibular apparatus
The vestibule contains 2 chambers. What are they?
utricle and saccule
Located on the inside surface of each utricle and saccule, is s small sensory area called a ___________
macula
The macula of the utricle lies mainly in the ______________ plane
horizontal
(this means the utricle is good at detecting vertical displacement)
The macula of the saccule is located mainly in a ______________ plane and signals head orientation when the person is lying down
vertical
(this means the saccule is good at detecting horizontal displacement)
Each macula is covered by a gelatinous layer in which many small calcium carbonate crystals called statoconia are embedded. All together this is called the ___________________. Hair cells project cilia up into the gelatinous layer
otolithic organ
macula receptors embedded gelatinous substance- otolithic membrane, this can detect gravity
The bases and sides of the hair cells synapse with sensory endings of the ____________ nerve
vestibular
Each hair cell has about 100 small cilia called ___________, plus one large cilium called the kinocilium. The kinocilium is always located on one side. When the stereocilia bend in the direction of the kinocilium, the filamentous attachments tug in sequence on the stereocilia, pulling them outward from the cell body. This movements opens several hundred cation channels. When the stereocilia are bent toward the kilocilium, the impulse traffic increases. As orientation of the head in space changes and the weight of the statoconia bends the cilia signals are transmitted to the brain to control ________________
stereocilia, equilibrium
What makes up the vestibular division of CN VIII?
3 semicircular canals and 2 otolithic organs
What is the function of the vestibular division of CN VIII?
send info about linear and angular acceleration
Each semicircular duct has an enlargement at one of its ends called the __________. Ducts and ampulla are filled with a fluid called _____________
ampulla, endolymph
The __________________ is a small crest inside each ampulla. On top of this is a loose gelatinous tissue mass called the __________
crista ampullaris, cupula
Sensory hair cells have stereocilia projecting into the….
cupula (gel)
(deflection or movement of the cupula either activates or inhibits the hair cells changing the firing pattern)
As the 3 canals are arranged in orthogonal planes, rotation of the head in any direction is detected. What are the 5 things that can be detected?
1) motion
2) head position
3) spatial orientation
4) balance
5) posture
The 3 semicircular ducts in each vestibular apparatus, known as the ___________________________ semicircular ducts, are arranged at right angles to one another so that they represent all 3 planes in space
anterior, posterior, and lateral/horizontal
When the head suddenly begins to rotate in any direction, called ________________________, the endolymph in the semicircular ducts bc of its inertia, tends to remain stationary while the semicircular ducts turn. This mechanism causes relative fluid flow in the ducts in the direction opposite to the head rotation
angular acceleration
T/F: the function of the semicircular ducts is to maintain static equilibrium and maintain equilibrium during steady directional or rotational movements
false
The semicircular duct mechanism predicts that _________________ is going to occur
disequilibrium
Removal of the ________________ lobes of the cerebellum prevents normal detection of semicircular duct signals
flocculonodular
Vestibular ganglion in the internal auditory canal receives input from the hair cells of….
semicircular ducts, utricle, and saccule
Vestibular ganglion in the internal auditory canal receives input from the hair cells of semicircular ducts, utricle, and saccule. and enters the brainstem at the pontomedullary junction. Fibers travel to where?
cerebellum and vestibular nuclei
4 vestibular nuclei
-all together are called the vestibular area
-inferior, medial, lateral, and superior vestibular nuclei
-each receptor has its own termination pattern and connections
The vestibular nuclei receive inputs from who?
-spinal cord (adjust posture)
-cerebellum
-contralateral vestibular nuclei
-brainstem nuclei involved in seeing movement
-thalamus to cortex (conscious awareness)
The vestibular apparatus detects the orientation and movement only of the _________. It is essential that the brainstem also receives appropriate info about the orientation of the head with respect to the body. This info is transmitted from the proprioceptors of the neck and body directly to the vestibular nuclei
head
What are the 4 vestibular nuclei?
inferior, medial, lateral, and superior vestibular nucleus
Which 2 tracts go to the vestibular area?
posterior spinocerebellar tract and spinovestibular
What tract connects CN 3, 4, and 6?
medial longitudinal fasciculus (MLF)
Movement of the head stimulates both canals of the vestibulospinal tract and their otoliths which further stimulates the vestibular nerve and its nucleus. The signals are relayed down to the lateral and medial vestibulospinal tracts and then to the spinal cord. The lateral tract helps in stimulating extensor muscle motor neurons in the legs in order to….
maintain posture and balance (keep you upright)
Movement of the head stimulates both canals of the vestibulospinal tract and their otoliths which further stimulates the vestibular nerve and its nucleus. The signals are relayed down to the lateral and medial vestibulospinal tracts and then to the spinal cord. The medical tract is only ___________. It stimulates muscles that support the ___________
cervical, head
