Motor Unit Flashcards
Withdraw limb from a painful stimulus
Automatically chew, swallow, breath, walk.
Automatically maintain our balance and posture
All functions of motor units
Perform complex, intricate voluntary movements like pick up a pencil; handwriting; Play piano; play golf; communicate through speech and gestures.
Function of motor unit
Voluntary motor control is the ability to
plan, coordinate and execute complex movements…in humans, this is incredibly sophisticated:
ability of humans to carry out skilled movements such as thinking and talking on a cell phone while driving a car, speaking while walking requires flexibility and skills and a _________that no other animal has.
motor control system
Sensory: Information enters sensory system through ______. Physical energy is transformed into ________ and information ascends through neural pathways (tracts) to______. Generates an internal representation of the world.
receptors
neural signals,
cortex
Motor: Programming begins in_____ and _______ and information is sent down through stages to ultimately, move muscles (effectors).
cortex
lower CNS levels
Motor processing begins with an internal representation of the _______
desired movement.
Motor control is:
hierarchical
Smaller, simpler elements at _______are integrated into more complex patterns at higher levels of the nervous system ________.
(at spinal cord)
brainstem, cortex
Successively higher levels of the motor hierarchy specify increasingly more
complex aspects of a motor task.
Motor control is :
parallel and redudant
What influences our final motor pathway (LMNs)
higher motor commands from brain with sensory influence
what are the 3 major components and levels of motor controll
Sp cd
Brainstem
Cortex
Motor areas of cortex influence the spinal cord ________ via descending systems from brainstem.
directly, or indirectly
All 3 levels are modulated by two independent subcortical structures:
- Basal ganglia
2. Cerebellum
The thalamus is a relay station for information from the_______ and ________ to the cortex
basal ganglia ⇒ cortex, and the cerebellum ⇒ cortex.
Caudate nuclues, putamen, globus pallidus , substantia niagra, subthalmic nucleus
part of BG
Two types of neurons in sp cd are:
Motor neurons in ventral horn
interneurons in intermediate zone
Motor neurons are in ______ and project to _______
ventral horn
right to muscles
these are LMNs!!!! and cause movement of body and limbs
LMNs are
motor neurons that project right to muscle and are the FINAL COMMON PATHWAY
motor neurons that project right to muscle and are the FINAL COMMON PATHWAY
LMNs
Interneurons are in the _______ and project to
intermediate zone motor neurons (2 types)
2 types of Interneurons
Segmental and Propriospinal
interneurons that project within a single spinal cord level.
segmental
Interneurons in intermediate zone
interneurons that transmit info between multiple spinal cord levels.
propriospinal
Interneurons in intermediate zone
Form circuits that help connect and coordinate motor neurons that contract groups of muscles for specific tasks
Interneurons
Interneurons fnx to
help connect and coordinate motor neurons that contract groups of muscles for specific tasks
Medial motor neurons innervate what:
proximal trunk, axial muscles
Medial motor neurons fnx:
control balance, posture, momevent of trunk… KEY FOR CORE CONTROL
Lateral motor neurons innervate
limb muscles
Lateral motor neurons fnx:
control movement of specific limbs/digits
–> motor neurons control proximal limbs more medial and distal limbs are more lateral
Brainstem: Modulates the action of
spinal motor circuits
Motor neuron in Brain Stem:
Motor nuclei with motor neurons that ________
They are what type of motor neuron?
directly innervate facial muscles.
LMNs
Lower motor neurons. (ex: Facial nucleus: Motor neurons that control muscles of facial expression; Hypoglossal nucleus: Motor neurons that controls muscles of tongue)
Motor neurons in the brain stem
Modulate spinal cord: Many groups of neurons that project down and terminate on neurons in the spinal cord gray matter.
Upper motor neurons in brain stem
UMNs from the brain stem project down and terminate on
neurons in the spinal cord gray matter
Medial brainstem pathways:
There are 3 of them
Tracts are named based on origin and end points.
Reticulospinal, Vestibulospinal, Tectospinal tracts.
Tracts descend in medial ventral white matter and terminate in the ventromedial area of the ventral spinal cord. Influence axial, proximal muscles.
Medial brainstem patwhays
Medial brainstem pathways: reticulospinal, vestibulospinal and tectospinal provide:
Provides basic postural control system upon which the cortical motor areas can organize more highly differentiated movement.
Lateral brainstem pathways:
Rubrospinal tract (Red nucleus ⇒ spinal cord).
Rubtospinal Tract descends in _______and terminates in the __________
dorsolateral white matter
dorsolateral area of the ventral spinal cord.
Influence motor neurons that control distal muscles of limbs. ** Modulate goal-directed limb movements like reaching and manipulating.
Rubrospinal tract
Rubrospinal tract functions:
influence motor neurons controlling distal musles of limbs
modulates GOAL DIRECTED movements like reaching an manipulating
MOdulates action of motorneurons in brainstem and sp cd (top of heirarchy)
Cerebral cortex
By sending descending commands to motor neurons in sp cd and brainstem, the cerebral cortex gives us the ability to:
organize complex motor acts and execute fine movements with precision.
Functions of the primary motor neurons
executes commands to motor neurons
coordinates force and direction of mvmt
contains somatotopic map of body (CONTRALATERAL)
executes commands to motor neurons
coordinates force and direction of mvmt
contains somatotopic map of body (CONTRALATERAL)
Primary Motor Neurons
Supplementary motor area is important in:
Important in internally-driven, will-driven movements…formulate an intention to make a movement.
primary somatosensory cortex
regulates incoming sensory info in the dorsal horn (info from medial lemniscus and anterolateral tracts)
Posterior parietal cortex will
help localize where object is with respect to body and helps motor system coordinate reaching in right direction for an object
Flex left index finger and see increase in BF in the:
Primary motor cortex area on the right side
Rapidly touch each finger of left hand to thumb, you see increase in BF in:
the RIGHT primary motor cortex AND
the LEFT and RIGHT supplementary areas (lots of increase)
Why do we see increase in blood flow to Supplementary Motor Area in both sides of the body when we rapidly touch each finger of left hand to thumb
because this area is under BILATERAL control
Where do we see increase of blood flow when we mentally reherese complex finger tapping?
See mild increase of blood in supplementary motor are on both sides
area key in planning complex, internally generated movements
Supplementary motor area
The cerebral cortex acts on motor neurons via two descending pathways:
1) Lateral corticospinal tract-contralateral limb, digits; goal-directed reaching
2) Ventral corticospinal tract-neck, trunk muscles; postural control
Lateral corticospinal tract fnxs
-contralateral limb, digits; goal-directed reaching
Ventral corticospinal tract fnxs
neck, trunk muscles; postural control
Lateral corticospinal tract descends in the ________ and terminates in the ______
dorsolateral white matter
lateral ventral horn
Ventralcorticospinal tract descends in_______ and ends in______
ventromedial white matter
medial ventral horn
Lower neural structures are concerned with more ______
while complex, voluntary neuromuscular tasks require ________
simple tasks
higher order brain structures
***Concept of Heirarchy
Concept of heirachically arranche motor systems benefits
fast and automatic reflex, congnitive motor activites take more time, E and neural processing, and we preserve cortex for more complicated tasks
Different systems operate in_______.
parallel
Parallel motor pathways exist between the______ and spinal cord (corticospinal tracts) and the_______ and spinal cord (brainstem tracts).
cortex
brainstem
Benefits of redundancy
When cortical, brainstem or spinal cord lesions occur, alternative pathways can partially compensate and carry out motor tasks such that person can still have basic motor functions. Redundancy gives flexibility and plasticity after injury.
Somatotopic organization exists at
each level of the motor pathway
simple, involuntary coordinated patterns of muscle contraction and relaxation evoked by peripheral stimuli.
Reflex movements:
Reflex movements involve the:
Involve spinal cord, motor neurons, sensory neurons, sometimes brainstem neurons.
What is the importance of reflexes?
Higher level motor control systems make use of simple reflex circuitry to coordinate muscles during complex, purposeful movements.
2) Reflexes are tested clinically to diagnose level of lesions/damage.
more complex, flexible than reflexes. Involve brainstem, spinal cord, motor neurons.
Automatic postural adjustments:
Automatic postural adjustments involve
brainstem, sp c and motor neurons
If you are tipping on a boat…what type of movement helps you stay upright
autonomic postural movements
Autonomic Postural adjustments:
Info about your posture is conveyed by _______ (inner ears) to midbrain.
vestibular system
Atuonmic Postural Adjustments:
Descending motor pathways from brainstem to spinal cord and motor neurons make a
compensatory shift in mass to your maintain balance.
Organized around a purposeful act… movements are goal directed and flexible
Voluntary movements
What is involved in voluntary movements
cerebral cortex, brainstem, sp cd and motor neurons
Voluntary movements will improve with practice because
Nervous system learns to anticipate and correct for envirnonmental obstacles
