Voluntary movement Flashcards
Cellular organization of the cortex in layers
I input II input III input (thalamus) IV input (thalamus) V major output VI output local
where are the corticospinal neurons
layer V
most stimuli activate several muscles (corticospinal axons diverge to motor neurons innervating more than 1 muscle)
simple movements of single joint
redundancy in muscle representation allows different combination of muscle activity for different tasks
Somatotopical organization (the homunculus)
primary motor cortex (M1)
motor areas of the cortex associated with voluntary movements
primary motor cortex (M1)
premotor cortex (ventral, dorsal)
supplementary motor area
cingulate motor area
areas for primary sensory cortex
3, 2, 1
areas for secondary sensory cortex
5 and 7
area for frontal cortex
46
working memory and spatial relationships
frontal cortex
Primary motor cortex properties
voluntary controlled movements (primarily simple mvmnts of hand and face)
somatotopic organization if highly plastic
Direct relationship b/w firing rate of M1 cells and force
Direction of movement is encoded by M1 neurons = population vector
critical for planning movement
project largely to primary motor cortex but also directly to spinal cord
stimulation evokes more complex movements involving multiple joints and resembling coordinated movements
damage to any of these causes more complex motor deficits than damage to M1 alone
Premotor areas
projects largely to proximal muscles
fires during delay between cue and actions
PMC d (dorsal)
projects more to hand and digit muscles
hand to the correct shape for manipulating a specific object
active whether the subject watches or performs the task
PMC v (ventral)
projects to M1 and SC
projections to SC largely to muscles of hand and digit
SMA
SMA properties
sequential movements mental rehearsal (internally driven movements)
Stimulation of SMA evokes
bilateral movements
coordinates movements on the two sides of the body
output pathways
corticospinal corticobulbar rubrospinal tectospinal vestibulospinal reticulospinal
largely controls voluntary movement and fine motor control
lateral corticospinal tract
largely controls the neck and trunk
ventral corticospinal tract
corticospinal tracts influence lower motor neurons via
direct excitatory connection to an alpha motor neuron
interneurons (which connect to alpha motor neurons) (excitatory - multijoint movements, inhibitory - modulate reflexes)
rubrospinal originates
red nucleus
rubrospinal crosses in
immediately in pons
function of the rubrospinal
gross motor movements, primarily upper limb flexion
vestibulospinal originates
medial- medial and inferior vestibular nuclei
lateral- lateral vestibular nuclei
tectospinal originates
superior colliculus
vestibulospinal funcitons
medial- controls head and back muscle to stabilize head;posture
lateral- activates extensor LMN to maintain upright and balanced posture
tectospinal funciton
reflexive turning of the head
function of reticulospinal
general movements; postural movements
reticular formation
general alerting area of nervous system
medial reticulospinal originates
pontine
lateral reticulospinal originates
medullary
descending spinal tracts; lateral pathways concerned with
goal directed limb movement
descending spinal tracts; media pathways concerned with
postural control system
UE flexion synergy components
scapular retraction/elevation or hyperextension shoulder abduction, external rotation elbow flexion forearm supination wrist and finger flexion
UE extension synergy components
scapular protraction shoulder adduction, internal rotation elbow extension forearm pronation wrist and finger flexion
LE flexion synergy components
Hip flexion, abduction, ER
Knee flexion
ankle DF inversion
toe DF
LE extension synergy components
hip extension, adduction, IR
Knee extension
ankle PF, inversion
toe PF
network of interneurons in brainstem and spinal cord
stringing together of reflexes; one triggering the next
rhythmic movements, adapted by higher brain centers
central pattern generators
neurons with axons that descend from cerebral cortex or brain stem and end on lower motor neuron
upper motor neuron
CN in brain stem or spinal cord and ends in skeletal muscles
Lower motor neurons
spontaneous contractions of groups of muscle fibers visible through the skin as small twitches
fasciculations
spontaneous contraction of individual muscle fibers, not grossly visible but apparent in electrical recordings
fibrillations
a rapid series of alternating muscle contractions in response to sudden stretch
clonus
UMN clinical signs
paresis
spasticity
Hypertonia
Hyperreflexia
LMN clinical signs
Loss of reflexes
atrophy
flaccid paralysis
fibrilations/fasciculations
