Unit 2_Vestibular Flashcards
What do the following describe?
- Monitors and regulates position of head and neck in space
- Monitors and stimulates head and body righting reactions
- Balance reactions
- Eye fixation in space while the head moves
Vestibular Functions
Where are the following structures found?
Part of the inner ear
3 canals
- Anterior
- Posterior
- Horizontal
Utricle
Saccule
Vestibular Apparatus
What vestibular structure is found on the horizontal plane, fast acceleration in car? Stimulated by movement in a horizontal plane.
Utricle
What vestibular structure is found on the vertical plane, elevator acceleration? Includes hair stimulated by movement in vertical plane.
Saccule
What vestibular structures contain sensory receptors-hair cells?
- Hair cells sit in Maculae
- Otolothic membranes lie over the maculae
- Calcium carbonate crystals or otoconia are on membrane
Otoliths
What vestibular structures are organized to detect tilt of the head, monitor linear acceleration, monitor head position with respect to gravity-static equilibrium?
Saccule and Utricle
What can’t the Saccule and Utricle differentiate in a singular plane?
Head tilt / acceleration
What does the semicircular canal pick up on?
Head tilt
What vestibular structure features bilateral symmetry to help us understand that our head is moving in a 3 dimensional space?
Anterior/Posterior Semicircular canals
What are endolymph filled canals that connect to the utricle?
- Widened ends called ampulla
- Crista ampullaris in the ampulla contain hair cell receptors
- Cupula overlies crista ampullaris
Cupula moves when head moves which bend hair cells and fires off action potentials in CNVII
- Sense angular rotational movements of the head
- Sense velocity of the head movements
Semicircular canals
What structures in the vestibular labyrinth transduce mechanical stimuli into neural signals?
Hair cells
What is the degree of exactness?
Fidelity
Difference between sides increases ________ of signal.
Fidelity
What is the Vestibular Ocular Reflex Goal?
Keep eyes on target
What do the following steps describe?
- 1st order neurons in Scarpa’s ganglion
- Peripheral process contact hair cells
- Central process forms CNVIII
Join the auditory portion of CNVIII - Enter brainstem at pontomedullary junction
Vestibular pathway to brainstem
What do the following steps describe?
- Directly to cerebellum
- Vestibular nuclei
- Cerebellum-balance
- Spinal cord Lateral Vestibulospinal tract (LVS) –postural response
- Spinal cord Medial Vestibulospinal tract (MVS)-head righting
- Spinal cord Reticulospinal tract (RST) -balance
- CN Nuclei for extraocular muscles vestibuloocular reflex (VOR)
- Cortex-conscious perception of balance
- ANS and reticular system-nausea etc. - Vestibulo-ocular reflex (VOR)
- Vestibulospinal reflex (VSR)
Vestibular pathway (once it gets to the brainstem)
What neuropathology includes the following:
- Normal reflexive response to rotation
- Slow and fast phase
- Can be inhibited
- Pathological if present at rest with minimal stimulation lasts excessively long
- Spontaneous, positional or gaze evoked
Nystagmus
What neuropathology is associated with the following symptoms:
Balance dysfunction
Abnormal VOR
Abnormal nystagmus
Nausea
Vertigo
Lesion CNVIII or inner ear or VN
What are some vestibular neuropathologies?
Loss of blood supply - Labyrinthine (Internal auditory) arteries
Benign Paroxysmal Positional Vertigo (BPPV)
Meniere’s disease (hearing loss, tinnitus, dizziness, nystagmus, nausea, vertigo)
Motion Sickness
Acoustic Neuroma
