Vestibular System Flashcards
Inner ear is called the ____
labyrinth
Osseus Labyrinth components (3)
Cochlea
Vestibule
Semicircular Canals
Membranous Labyrinth Components (4)
Cochlear duct
Utricle
Saccule
Three semicircular ducts
Endolymph is high in
Potassium
Perilymph is high in
Sodium
Vestibule
Large chamber adjacent to the middle ear
Semicircular canals
Three semicircular channels in bone, each is orthogonal to the other two
Cochlea
spiral chamber that is related to hearing
Membranous Labyrinth contains:
endolymph
Cochlear duct
Related to hearing
Utricle
Larger of 2 sacs within the vestibule
Contains Otolith membrane and macula
Saccule
Smaller of 2 sacs within the vestibule
Contains otolith membrane and macula
3 semicircular ducts
Each have an ampulla which contains a crista ampullaris and a cupulla
Crista Ampullaris
crest bearing sensory receptor cells
Cupulla
Gelatinous membrane
The Vestibular Apparatus Consists of (3)
Macula of the utricle
Macula of the saccule
Crista ampullaris
Macula of the utricle
Horizontally oriented and detects LINEAR ACCELERATION in the horizontal plane (side to side)
Macula of the saccule
Detects LINEAR ACCELERATION in the vertical plane (up and down)
Crista ampullaris
1 in each semicircular duct ampulla
Detects ANGULAR ACCELERATION directed along the plan in which the duct is positioned
Movement of the overlying otolith membrane results in deflection of ______
Sterocilia
Deflection TOWARD the kinocilium mechanically opens ion channels. This allows ______ to flow from endolymph into the hair cell, thus _______ the receptor cell membrane
Potassium
Depolarizing
Depolarization of the receptor cell enables _____ influx and release of ______ from synaptic vesicles which are located along the basolateral region of the receptor cell. The ______ neurotransmitter triggers action potentials in afferent axons on the vestibular nerve.
Calcium
Glutamate
Deflection away from the Kinocilium _____ ion channels and ultimately _____ glutamate release
Closes
Reduces
In the crista ampullaris, sterocilia are embedded in a geltanious membraned called a ______
Cupula
In the macula, stereocilia are embedded in a gelatinous _______
Otolith Membrane
Otolith membrane contains
Calcium concretions (ear stones)
Receptor cells are ______ active and vestibular nerve axons _____ conduct action potentials to the brainstem. Thus the movement of sterocilia results in an ______ or a _____ in the rate of spontaneous activity.
Spontaneously
Continually
Increase
Decrease
Vestibular nerve fibers (axons from the neuronal cell bodies of the vestibular ganglion) travel from the ___ ___ to the ____
Inner Ear
Brain
Vestibular nerve fibers synapse in _____ _____ of the brainstem and in the ___ or ____ of the cerebellum.
Vestibular Nuclei
Nodulus or flocculus
Four vestibular nuclei are located bilaterally in the medulla and the pons. The nuclei receive input from the _______ and project to: (4)
Vestibular Nerve
- Cerebellum (flocculu-nodular lobe)
- Reticular formation
- Spinal cord via the lateral vestibulospinal tract activates limb extensor mm via alpa and gamma neurons
- Neurons controlling eye and neck mm via the MEDIAL LONGITUNDINAL FASCICULUS
Eyes are shifted in a direction ____ to the direction that the head is accelerated
Opposite
Vestibular nuclei on the right side dominate activity in the ______ Abducens nucleus and _____ Oculomotor nucleus, causing both eyes to move _____
Left
RIght
Left
In general, vestibular nuclei push the eyes _______
contralaterally
Extensor muscles are contracted ________ which the head is accelerating
on the side toward
Vestibular Syndrom symptoms (3)
Head Tilt
Stumbling
Nystagmus
Slow phase of nystagmus is directed ____
toward the side of the lesion
Vestibular nystagmus is generated reflexly by ___ ___ in response to angular accelreration
Vestibular
Opticokinetic nystagmus is generated by ____ when focusing on moving objects (e.g. a train passenger focusing on telephone polls)
Cerebral cortex
