Vestibular System Flashcards
List and describe the 3 ear divisions
- outer = capture sound waves
- middle = convert waves to vibrations
- inner = convert vibrations to nerve impulses
Which structure of the ear also aids in maintaining balance in space?
Inner ear
What is the specialized cell that aids in balance that contains nerve endings and mechanoreceptors?
Stereocilia
The outer and middle ear are innervated by which nerves?
Auricular and facial n
Describe Inner ear innervation
CN 8 - vestibulocochlear
Where is the internal ear located?
Petrous part of temporal bone
Which labyrinth contains perilymph?
Bony labyrinth
Endolymph is located in?
Membranous labyrinth
The cochlear duct has ___________ function and ___________ sound processing
Auditory; sensory
In the inner ear, which structure is associated with balance?
Semicircular duct
The semicircular duct lies in the ________________ of the bony labyrinth
Semicircular canal
How many semicircular canals in the bony labyrinth?
3
The __________ connects the cochlea to the semicircular canals
Vestibule
Define the cochlear
Spiral tunnel around axis of spongy bone called modiolus
The enlarged portion of the semicircular ducts is called the?
Ampulla
Within the ampulla is a specialized innervation called the _____________ that contain the hair cells?
Crista ampularis
The _________ and ___________ are housed in 2 depressions of the vestibule
Utricle and saccule
What are the 3 semicircular canal pairs?
- posterior
- anterior/superior
- horizontal/lateral
Which semicircular canal is concerned with dynamic position of the head in 3 perpendicular planes??
Horizontal/lateral
True or false: The lateral semicircular canal pair is sensitive to constant velocity rotation
False
List the 2 otolith organs
- utricle
- saccule
Linear acceleration and static position of the head are associated with which otolith organ?
Saccule
Type 1 hair cells are characterized by ?
Narrow neck and rounded base
Type II hair cells are _______________ in shape
Cylindrical
Which type of hair cells are likely only inhibitory?
Type I
True/False: Type 2 hair cells are innervated only by afferent fibers
False, they are innervated by both
Where do afferent fibers direct their projections to?
CNS
Where does bending need to occur to depolarize the cell (activate it)?
Towards kinocilium
Bending away from the kinocilium will ____________ the cell
Hyperpolarize/inhibit
What does the crista ampullaris contain?
Strereocilia (includes kinocilium), tip link, gelatinous cúpula, nerve supply
What are adjacent stereocilia linked by?
Tip links
Where do sensory hair cells project into ?
Gelatinous cupulla
What is the function of the cúpula?
Allow for uniform movement of hair cells
Cells in the macula are ___________ (flat/dome)
Flat
Describe endolymph movement when the head is moving
Endolymph moves opposite to the direction of the head
True/false: An increase in firing occurs toward the direction of the head
True
Define nystagmus
involuntary eye movement to stabilize the image on the retina
Describe rotational nystagmus
Eyes move slowly opposite to rotation and quickly in direction of movement
Which nystagmus is accompanied by vertigo and muscle contractions, appropriate for virtual rotation?
Post-rotational (reversed movements to rotational)
Describe the vestibulo-ocular reflex
Head turns left = output from left vestibular nucleus inhibits and excites right = eye moves right because of contraction and relaxation of muscles
*LR6
*DO4
Where are kinocilium embedded?
Gelatinous cupula
In the cupula, what is embedded that helps with hair cells movement?
Otoliths-Ca carbonate crystals
What is the midline between utricle and saccule?
Striola
Describe direction of stereocilia on each side of the striola
Opposite on either side of striola
Describe orientation of macula of utricle
Horizontally
Describe orientation of macula of saccule
Vertically
