Functional anatomy of balance Flashcards
what is the definition of balance
complex dynamic process involving musculoskeletal system, neurological system and cardiovascular system
how is balance commonly described
the constant fight against gravity
how is posture maintained
constant integration of sensory inputs and modifications of motor outputs
what is the model of balance
PNS has stretch flexes, these are muscle contractions in response to stretching in order to maintain constant muscle length
these are spinal reflexes which are fast and travel short distances
inputs for maintenance of balance
eyes - vision and surrounding environment
inner ear balance organs - angular and linear acceleration of head)
muscles, joints, tendons and skin - self-movement, body position, proprioception and exteroception)
what organs process balance maintenance
cerebellum and brainstem
what is the output for maintenance of balance
reactive postural response
anticipatory postural adjustments
what is the vestibular system
main sensory apparatus of balance
where is the vestibular system found
inner ear
all structures are located within the labyrinth
contains vestibule, semi-circular canals (balance) and cochlea (hearing)
what is the labyrinth
a series of interconnected fluid-filled cavities inside the petrous temporal bone
what is the vestibule and its function
a chamber opening into another
oval structure at the centre of the labyrinth
has an utricle and saccule
function is to detect linear acceleration (head position with respect to gravity)
semi-circular canals and their fucntion
3 loops - anterior, posterior and lateral
anterior and posterior are in vertical plane at right angles, lateral is in horizontal plane
detect angular (rotational) acceleration
how is movement detected
cells of the vestibular system detect movement of fluid using mechanosensitive hair cells
what is the microstructure of the vestibular system
apical (epithelial) surface covered by cilia
cells are covered by an otolithic membrane (jelly-like structure containing many small crystals called otoliths)
how does movement affect the vestibular system
results in the otolithic membrane lagging behind the layer of hair cells due to inertia
hair cells act as transducers converting kinetic energy into nervous impulses
