Vestibular System Flashcards
What does the vestibular system monitor?
Balance and eye movement
What are the features of a vestibular cell
Microvilli - sense changes in proprioception of head
Cilium - one modified hair (like in cochlea)
What are otoliths?
Calcium carbonate structures in inner ear
What do otoliths detect? How?
Gravity and linear acceleration (walking in straight line)
Causes hairs to stretch/bend —> electrochemical signal to CN VIII
What are the semi-circular canals?
3 canals at right angles to each other
Filled with endolymph
Detect head rotation in all directions
What is the pathway from the semi-circular canals?
From CN VIII
To medulla oblongata and pons
To cerebellum, cerebral cortex, neck and extraoccular muscles
Which 3 reflexes govern posture?
vestibular reflex
Tonic neck reflex
Righting reflex
What is the vestibular reflex?
Enables postural adjustments in response to change in axis (slopes)
Shift centre of gravity to stabilise posture
What is the tonic neck reflex?
Propioceptors in neck detect and provide rest of NS with information of head position
WHat is the righting reflex? What does it use?
Correcting posture when fallen
Propioceptors in neck, vestibular system and pressure receptors in skin
Position head correct to gravity, then body, then extend limbs
What is the vestibulo-ocular reflex?
Stabilises retinal image during fast head movements
Extra-ocular muscles move simultaneously and opposite to head movement
What is the pathological condition where the vestibulo-ocular reflex fails when stood stil?
Nystagmus
What causes motion sickness?
Visual information conflicting with balance information
Stimulates vomiting centre in brain stem
What are symptoms of vestibular syndrome? What causes it
Head tilt
Circling
Nystagmus
Inner ear infection - causes asymmetric stimulation of postural and vestibulo-ocular reflexes
