Neuro Exam 3.5
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Neuro Exam 3.5
neurology neuroanatomy neuroscience
review of neuro lecture 5 for exam 3
What are the parts of equilibrium and balance?
What is the function of the vestibular system?
detects changes in motion and position of the head (respect to gravity and horizon)
Where does information come into the vestibular system from?
What happens when the equilibrium triad is not in sync?
problems with equilibrium
What are the parts of the equilibrium triad?
Which cranial nerve is associated with vision?
CN II: Optic Nerve
What is the dominant sensation in humans?
What characteristics of vision must be able to be maintained in order to have normal equilibrium?
constant, coordinated eye gaze
What determines head position?
plane of vision; adjust head to coordinate gaze
What is the VOR?
keeps your eyes pointed in a particular direction despite body movement
Which column deals with proprioception?
What is proprioception?
body position sense in context to gravity
What does proprioception influence?
muscle tone of neck to maintain plane of vision
Which cranial nerve is associated with vestibular system?
CN VIII: Vestibulochochlear nerve
Where is the vestibular system found?
What does the inner ear detect?
motion and position changes of the head
What anatomy makes up the vestibular system?
Where is the bony labyrinth located?
lateral portion of petrous portion of temporal bone
How many parts make up the bony labyrinth?
What are the 3 parts of the bony labyrinth?
What does the cochlea do?
What is the vestibule?
small oval chamber composed of utricle and saccule
What do the utricle and saccule detect?
How many semicircular canals are there?
What are the 3 semicircular canals?
What do the semicircular canals detect?
How are the semicircular canals arranged?
set at right angles to occupy 3 planes of space
What shape do the semicircular canals form?
2/3 of a circle
Where do the semicircular canals lie?
posterior to vestibule
What is the diameter of the semicircular canals?
about 1.5mm, except at ends where they are dilated
What are the dilated ends of the semicircular canals referred to as?
bulge along semicircular canals that contain hair cells of semicircular canals
Which way do the ampulla face?
towards the vestibule
fluid w/in the bony labyrinth
Where is the membranous labyrinth?
inside bony labyrinth
What is the membranous labyrinth?
system of sacs and ducts that communicate w/ and are suspended w/in the bony labyrinth
What type of fluid in in the membranous labyrinth?
endolymph--characteristics are identical to perilymph
What are the 3 parts of the membranous labyrinth?
utricle and saccule
3 semicircular ducts
Where are the utricle and saccule found?
vestibule of bony labyrinth
What system are the utricle and saccule a part of?
Do the utricle and saccule communicate with each other?
What system are the semicircular ducts a part of?
Where are the semicircular ducts found?
in semicircular canals
What are the enlarged ends of the semicircular ducts referred to as?
What is the sensory area of the ampulla?
sheet of hair cells of the semicircular canals
Where is the cochlear duct?
sits in cochlea (part of bony labyrinth)
What is the cochlear duct responsible for?
What is the functional area of the semicircular canals?
gel that spans the lumen of the canal w/in the ampulla; cilia project into cupula
What do the cilia of the cupula make up?
sensitized hair cells (75-100 stereocilia/microvilli)
one tall (large) cilium per each hair cell that detects the direction in which the hair cells bend as a result of head movement
What is another name for Kinocilium?
What does movement of the head cause?
endolymph to move and bend the hair cells
What happens when the hair cells bend toward the kinocilium?
cell membrane stretches, opening K channel (K influx)
depolarization that results in opening of voltage-gated Ca channels (Ca influx)
Ca influences exocytosis process
What happens if the hair cells bend away from kinocilium?
hyperpolarizaiton (inhibits cell)
What happens if the hair cells bend toward kinocilium?
depolarization (excitatory receptor potential)
What does depolarization cause?
membrane to release NT
What does the NT influence?
1st order sensory neurons in equilibrium pathway (CN VIII)
What type of potential occurs at the 1st order sensory neurons in the equilibrium pathway?
generated potential (type of graded potential)
AP occurs w/ enough depol
What does the crista ampullaris respond to?
angular acceleration and deceleration, but not constant movement
While rotation excites the hair cells of one canal, it:
inhibits the hair cells of contralateral partner
All bending of hair cells occurs in:
What do the utricle and saccule contain?
hair cells similar to the semicircular canals
tiny crystals of calcium carbonate that move in the endolymph function to add energy dissipation and amplify the message for movement
What do the utricle and sccule together detect?
linear acceleration (moving forward/backward)
How is the utricle positioned?
What does the utircle detect?
lateral bending of head/neck
How is the saccule positioned?
What does the saccule detect?
flexion/extension of head/neck
up and down changes
There is some overlap b/w the crista amullaris/utricle/saccule--but for the most part:
each is responsible for the functions listed
What are hair cells?
Hair cells depolarize to dump:
NT into synaptic cleft, which influences receptor organ at distal end of 1st order neuron (CN VIII)
Where are the cell bodies of hair cells located?
Where does CN VIII go to synapse w/ 2nd order?
Where is nystagmus seen?
movement of eyes beginning w/ slow movement to one side then rapid movement in opposite direction
What are the stages of nystagmus?
What is the rapid phase called?
What is the slow phase called?
How are nystagmus named?
according to the rapid phase direction (right or left)
Nystagmus is malfunctioning vestibular system including problems with:
vestibular nuclei in pons
What is caloric nystagmus based on?
temperature in inner ear
How do you test for caloric nystagmus?
use cold or warm water in syringe
What does the water cause the endolymph to do?
move w/in semicircular canal more than saccule and more than utricle
As the endolymph moves in response to water temperature, what do the hair cells do?
move and result in nystagmus
What does cold water in the R ear do?
nystagmus of L
What does warm water in R ear do?
nystagmus of R
If there is no nystagmus with this test, there is a possible:
neurological issue going on
as head and body pivot/circle, the eyes attempt to fix on an object in space (slow component)
as head and body continue to circle, the eyes snap quickly in the direction that the head is circling (saccade)
The action from rotational nystagmus is similar to what happens when you watch:
telephone poles from a moving train: saccade occurs in direction train is moving
What happens to eye movements during rotational nystagmus?
repeat throughout duration of circling
Which way does nystagmus occur in rotational nystagmus?
direction you spin