motor planning
formulating a strategy of action by specifying motor goals
motor goals
tend to be the setting of spatial and temporal (sequencing) targets rather than explicit commands for which muscles should contract
apraxia
inability to execute skilled, learned motor acts acts despite preservation of motor and sensory systems , comprehension, cooperation and coordination.
Types of apraxia
ideomotor, ideational, apraxia of speech, oral and nonverbal apraxia
ideamotor apraxia
inability to pantomime, imitate and use tools properly. Can affect communication gestures too
motor planning in apraxia of speech
we don't hear errors due to muscle weakness or spasticity because it is the early stage of the motor process and is not responsible for sending commands to muscles.
Motor programs (Van der Merwe)
specify muscle tone, direction, range and rate of movement which can be modified and updated in real time
Motor plans (Van der Merwe)
are not modified in real time
area of occurrence of motor planning
primarily in the cortical motor association cortex
premotor cortex
supplementary motor cortex
parietal association cortex
Broca's area
portions of insula and basal ganglia
area of occurrence of motor programming
structures in the middle level of motor control hierarchy:
basal ganglia, cerebellum, premotor and supplementary motor cortex.
pyramidal system
responsible for voluntary movements in speech and in limbs
origin of pyramidal system
the cortex
2 tracts that make up pyramidal system
corticospinal tract & corticobulbar tract
beginning of corticospinal tract
primary motor cortex (some axons begin in premotor & supplementary cortex)
location of decussation of corticospinal tract
lower medulla
corticospinal tract innervation
muscles and limbs
damage to corticospinal tract above medulla
results in damage to contralateral side
damage to corticospinal tract below medulla
results in ipsilateral damage (same side)
beginning of corticobulbar tract
cerebral cortex (primary motor cortex)
termination of corticobulbar tract
different cranial nerves at different level of the brainstem.
termination of corticospinal tract
different level of spinal cord
decussation of corticobulbar tract
at level of cranial nerve nuclei that they are supposed to innervate.
corticobulbar tract innervation
muscles of head and neck, all muscles for speech and swallowing except muscles of respiration.
descending pathways of pyramidal tract
corona radiata
internal capsule
crus cerebri
lesions in the internal capsule
greater chance of widespread impairment since the fiber pathways are closely packed at this level.
direct motor system
name for both corticospinal and corticobulbar tracts
lower motor neurons
exist partly in CNS and partly in PNS
location of cell bodies for cranial nerves
brainstem
location of cell bodies for spinal nerves
spinal cord
motor unit
lower motor neurons, axons of these cell bodies, the myoneural junction, each muscle fiber innervated by this nerve.
muscles of limbs
receive unilateral, contralateral innervation
muscles of head and neck
receive bilateral innervation
paralysis
gross limitation of movement
paresis
incomplete paralysis
upper motor neuron damage
hypertonia & hyperflexia
hypertonia
spasticity, increase in tone, reistance to passive stretch
hyperflexia
exaggerated muscle stretch refelx assoc with spasticty, weakness, can affect muscles involved in speech production
lower motor neruon damage
hypotonia, atrophy, hyporeflexia
hypotonia
reduced muscle tone resulting in paralysis and paresis
atrophy
loss of muscle bulk due to lack of innervation
hyporefelxia
reduced reflex response