Cognitive/motor 3 Flashcards
what does motor control involve
many brain areas
what consciously initiates movement
higher centers - frontal portion of brain
motor cortex= sends axons down spinal cord
describe middle level
like basal nuclei
Executes individual muscle contractions
make corrections based on sensory info (takes into account feedback from sensory organs)
middle layer - thinks about all muscle contractions or relaxations
name and describe the 2 descending tracts
corticospinal - skilled movements, innervate hands and feet
extrapyramidal, trunk and posture - comes out of neurons from brainstem driven by middle layers, involved in automatic changes in trunk and posture we do not think about, like reach for coffee = automatically contract in muscles to compensate = mediated by extrapyramidal pathways
what are receptors
like muscle spindle and golgi tendon organ
what do voluntary movements have
involuntary component
describe voluntary control of movement
central sulcus
Consciously initiate movement –> premotor cortex –> starts planning of what has to happen for movements to occur –> primary motor cortex - neuron will activate and send axons down spinal cord (sits in front of somatosensory cortex)
Together = sensorimotor cortex (primary motor cortex)
describe organization of primary motor cortex
some areas in motor cortex takes up a lot more surface area
corresponds to parts of body with highly skilled movements and have many muscles to be controlled
describe somatotopic motor representation
1) Systematic relationship between select muscle groups and the body areas they control- body layed out in organized Fashion
2) Size of body structures in primary motor cortex is proportional to the number of neurons dedicated to their motor control.
3) Size of body structures in primary motor cortex is proportional to the degree of skill required to operate that area of the body.
Describe direct cortical control of movement - gen
2 major descending pathways
alpha gamma motor neuron’s send axons down from primary motor cortex
describe corticospinal pathway in detail
skilled movements
direct control
unqiue since directly activates motor neurons
crosses in medulla - contralateral control of body from motor cortex
directly innervates alpha and gamma motor neurons
describe extrapyramidal pathway in detail
trunk and posture
contract and relax trunk muscles, middle layers of motor cortex
interneurons and gray matter
indirect activation of alpha and gamma motor neuron’s since activate interneurons
describe corticospinal motor pathway - 5 statements
1) Originates in primary motor cortex (precentral gyrus). 2) Compact, discrete fiber tract direct to spinal cord.
3) Crossed: Controls contralateral muscles.
4) Extremities: Predominantly hands and feet.
5) Controls skilled voluntary movements.
describe extrapyramidal motor pathway - 5 statements
1) Originates from neurons in brainstem.
2) Diffused and indirect: Several descending tracts via the brainstem.
3) Crossed and uncrossed. - ips and contralateral control
4) Trunk and postural muscles.
5) Controls upright posture, balance, and walking
what is muscle tone
Resistance of skeletal muscle to stretch
describe muscle tone of normal subject
slight and uniform
how can muscle tone be damaged
damage to descending pathways
damage to motor neurons
describe damage to descending pathways - muscle tone
mostly extrapyramdial and some corticospinal - mainly inhibitory
could be due to spinal injury overactive
hypertonia = abnormally high muscle tone
spasticity = overactive motor reflexes (how to know if patient unconscious)
rigidity = constant muscle contraction
describe damage to motor neurons - muscle tone
hypotonia - abnormally low
muscle tone
Atrophy = loss of muscle masss
Decreased or missing reflexes
(Diseases that affect muscles themselves or neuromuscular junction)
describe basal nuclei - ganglia
helps determine specific sequence of movements needed to accomplish desired action
collection of cell bodies
do not notice you have a basal nuclei till things go wrong
name 2 basal nuclei moment disorders
parkinsons
huntingtons
describe parkinsons disease - gen
common in elderly
one of most common movement disorders
reduced dopamine input to basal nuclei
describe parkinsons disease -symptoms
akinesia = reduced movements
bradykinesia = slow movements
Muscular rigidity
resting tremor - when at rest
describe parkinsons disease - treatment
treatment = increase dopamine concentrations in brain
some promise from deep brain stimulation
describe huntingtons disease - gen
genetic mutation that causes widespread loss of neurons in the brain
shows up later in life
neurons in basal nuclei are preferentially lost
describe huntingtons disease -symptoms
Hyperkinetic disorder = excessive motor movements
choreiform movements = jerky random involuntary movements of limbs and face
describe cerebellum
Movement, timing, planning and error correction
learning new motor skills
recieves sensory info - vestibular, visual, auditory, somatosensory, proprioceptive
contains almost half of brains neurons
activates extrapyramidal descending pathway
keeps things moving smoothly during execution of movement
describe cerebellar deficits - asynergia
smooth movements are subdivided into their separate components like stop motion
doing things step by step
usually cerebellum does it for you
describe cerebellar deficits - dysmetria
unable to target movements correctly “past pointing”
describe cerebellar deficits - ataxia
incoordination of muscle groups
awkward gate
describe cerebellar deficits - intention tremor
during voluntary movements
as motor command happening
describe cerebellar deficits - paralysis
no paralysis or weakness
generally function ok but do not have highly skilled motor control
