overview of motor systems Flashcards
roles of the motor system
- Allows us to move our body and limbs in space & maintain posture - Initiate movement & suppresses conflicting movements - Coordinates movement
____ sets of motor neurons allow us to move our body and limbs in space
2
Upper Motor Neurons mediate_______ control over movements
voluntary
Upper Motor Neuron cell bodies are located in the ________
cortex and brainstem
lower motor neurons are located in the of the spinal cord and in the ________ of the brainstem.
- ventral horn - cranial nerve motor nuclei
______ motor neurons mediate involuntary & voluntary control over movements
lower motor neurons
the final common pathway for involuntary & voluntary movements
lower motor neurons
axons of lower motor neurons contribute to _____ or ______
cranial nerves or spinal nerves
lower motor neurons innervate ______ at the neuromuscular junction
skeletal muscles
lower motor neurons are always ______
excitatory
NT as the lower motor neuron
Acetylcholine
Reflexes involve a defined neural circuit with sensory input and a motor output. No _______ required.
cerebral cortex
Descending UMN Pathways to LMNs
- lateral corticospinal tact LCST - corticobulbar tract -ventral corticospinal tract
neuron 1 in the _______ is called the upper motor neuron
precentral gyrus
uppor motor neuron travels in the _______
posterior limb internal capsule
90% of upper motor neurons decussate in the ______ and is called the ________
medullary pyramids, lateral corticospinal tract
upper motor neuron syndrom early signs
paralysis or paresis (weakness)
clinical signs of upper motor neuron syndrome
- Babinski sign (abnormal reflex) - Hyperactive deep reflexes - Spasticity, increased muscle tone, particularly in anti-gravity muscles - Little or no muscle atrophy (atrophy of disuse) - Decreased or absent superficial abdominal reflexes
clinical signs of lower motor neuron syndrome
- Flaccid paralysis (loss of movement) or paresis (weakness) - Loss of reflexes - Loss of muscle tone - Fibrillations and fasciculations—spontaneous twitches - Atrophy
A lesion of the precentral gyrus near the longitudinal fissure would most likely result in
increased muscle tone in antigravity muscles
UMNs in the premotor &motor cortex + axonal pathway that links them to LMNs
pyramidal system
basal ganglia, red nucleus & brainstem reticular formation form the
extrapyramidal system
receives the motor plan from the cortex and initiates movement
basal ganglia
suppresses conflicting motor programs
basal ganglia
output of the basal ganglia
thalamus
components of the extrapyramidal system
- basal ganglia
- substantia nigra
- sub thalamic nucleus
- red nucleus
- brainstem and reticular formation
label these
the basal ganglion input region
striatum - caudate and putamen
lentiform nucleus
the putamen + globus pallidus
pallidum
globus pallidus + substantia nigra + pars reticulata
the basal ganglia output region is the _____ and it goes to the _______and ______
- pallidum
- goes to the thalamus and red nucleus
The globus pallidus has 2 parts :
- GPi major output - direct pathway (increases movement)
- GPe - indirect pathway (decreases movement)
importnat in voluntary movements and making postural adjustments
basal ganglia
Movement is inhibited by which of the basal ganglia pathways?
indirect pathway
Which dopamine receptor in the striatum is inhibiting the indirect pathway of the basal ganglia to increase movement?
D2 receptor
•Summing up the excitatory and inhibitory circuitry (does/does not) allow us to predict the ultimate output of the system.
does not
Cerebellar functions
–Aid in equilibrium
–Provide smooth fluid movements
–Coordinating head & neck movements with eye movements
–Modulates on-going motor activity in accord with the motor plan.
–Error-correcting function.
–Motor “memory”
the cerebellum receives ___ different sources of input. Name them:
3
- vestibular system
- spinal cord sensory information
- cortical motor information
cerebellum vestibular input
–sensory information needed for coordinating balance and posture with head, neck, and eye movements
cerebellum input from the spiunal cord
–monitoring muscle performance of motor plan, making postural adjustments
the cerebellum receives corotical motor information via brainstem nuclei to receive the ______ plan
motor
Inputs and Outputs to the Cerebellum are through the _______
Cerebellar Peduncles
inferior peduncle function
inputs to the cerebellum
midde peduncle function
inputs only to the cerebellum
superior peduncle function
outputs only from the cerebellum
•Outputs from the cerebral peduncle have error correcting function providing indirect feedback to the
- cortex regarding execution of the motor plan
- muscles executing the plan
Clinical symptoms of impaired cerebellar function; symptoms appear on ____ side as the lesion.
same side
clinical symptoms of imparied cerebellar function
- reduced muscle tone
- dysmetria
- intention tremor
- ataxia
- asynergy
- dysdiadochokinesia
- disruptions in balance and coordinated eye movements with head movements
- loss of equilibrium
- nystagmus
asynergy
lack of coordination
dysdiadochokinesia
difficulty performing rapidly alternating movements
ataxia
clumsiness in movements; trunkal ataxia (druken gait)
dysmetria
movements tend to overshoot target
•The _____indirectly provides error-correcting feedback to the cortex regarding the on-going motor plan.
cerebellum
