motor system Flashcards
motor unit
a motor neuron and all of the muscle cells it innervates
___ provide the only input to muscles
lower (alpha) motor neurons
lower motor neurons found in
spinal cord(anterior gray horn) and brain stem
medial column-axial muscles
lateral column-more distal muscles of extremeties
what type of receptors are muscle spindles
sensory receptors
what is the result of the myotatic reflex
agonist muscles contract (alpha motor neuron)
antagonist muscles relax
what is the reverse of inverse myotatic reflex
1a and II are the sensory neurons
1b-causes agonist to relax and antagonist to contract
what types of neurons innervate intrafusal muscles
gamma motor neurons(proprioception)
produce changes in length of IF fibers to keep fiber sensitive
lower motor neuron lesion results in
flaccid paralysis and severe atrophy enduring flaccid paralysis hypotonia no superficial reflexes reduced or absent deep tendon reflexes fasiculations atrophy
corticospinal tract
volitional control, trunk and extremeties, fractionating finger movements, precision grip
corticobulbar tract
volitional control, muscles of mastication, facial expression, tongue, vocal cords
corticoreticular tract
voitional movements, cortical drive to neurons of reticulospinal tracts, reaching, power trip
reticulospinals tract
postural control of proximal limb and trunk
vestibulospinals
lateral-postural control
medial-part of system to coordinate head and eye movements
tectospinal tract
reflex originating movements of head and eyes in response to visual, tactile, auditory stimuli
origin of corticospinal tract
postcentral gyrus, primary motor cortex, premotor cortex, supple-mentary motor cortex
postcentral gyrus’
efference copy, informing sensory structures of motor plan to optimize proprioceptive feedback related to the planned movement
primary motor cortex
voluntary
finger movements
control of distal limb muscles associated with volitional movements
premotor cortex
voluntary
reaching and grasping
specific movement
proximal limb muscles
supplementary motor cortex
volitional movement
learning stimulus response asociations
mental rehearsal of skilled movements
inhibition of movement
corticobulbars originate from
lateral and inferior portion of precentral gyrus
descend with corticospinal to brainstem levels to control motor neurons associates with cranial nerves
corticospinals originate from
superior and medial regions and from premotor and supplementary motor cortices
descend to spinal cord to control motor neurons for the trunk and extremeties
corticobulbar tract is in
genu of internal capsule
corticospinal tract is in
posterior limb of internal capsule
lateral corticospinal controls
trunk and extremeties
anterior corticospinal controls
motor neurons that innervate neck soulder and upper trunk muscles
medially descending pathways
anterior corticospinal
reticulospinal
tectospinal
vestibulospinal
medial vestibulospinal tract function
participates with other structures to coordinate head neck and eye movements
lateral vestibulospinal tract function
promotes movements to maintain posture and balance; especially involved in reflex actions to maintain upright posture
tectospinal tract functions
to coordinate head movements and eye movements as part of reflex orienting to visual, auditory, and touch stimuli
medial rectospinal tract originates from
pons
lateral recticulospinal tract originates in
medulla
reticulospinal tract function
cooperate with vestibulospinal
maintain posture and balance
___only extend to upper thoracic spinal cord levels
anterior corticospinal and medial vestibulospinal tracts
damage to corticospinal tract results in
weakness especially in distal musculature of extremeties
what is muscle tone
the force with which a muscle resists being lengthened
babinski reflex indicative of
corticospinal tract damage
