Exam 4: Kletzel 1 Flashcards
Motor control centers (_____, ______) maintain posture and generate purposeful movement
What do the following terms mean:
- Postural stability
- Voluntary actions or praxis
Motor control centers (forebrain and brainstem) maintain posture and generate purposeful movement
- Postural stability: maintaining position during self-generated movements and against unexpected perturbations
- Voluntary actions or praxis: includes speech, facial expressions, reaching, grabbing, holding, etc
Explain what the following tracts are important for:
Medial Tracts
Lateral Tracts
Extrapyramidal Tracts
Medial Tracts: Posture
- lateral vestibulospinal tract (lvst)
- lateral and medial retuculospinal tract (lrst and mrst)
- ventral corticospinal tract (vcst)
Lateral Tracts: Praxis - control of appendicular and facial muscles
- lateral corticospinal tract (lcst)
- corticobulbar spinal tract
- rubrospinal tract (rst)
Extrapyramidal Tract: travel seperately, support nondeliberate emotional actions
Explain Complex vs Simple Types of Movement:
Complex
- ____ and ____ tracts
- ____ projections from motor control centers to motoneurons
- Examples?
Simple:
- ____ tracts
- ____ projections from motor control centers to motoneurons
- Examples?
Complex:
- corticospinal and corticubulbar tracts
- direct projections from motor control centers to motoneurons
- Examples: play piano, play rock paper scissors
Simple:
- All descending tracts
- Indirect projections from motor control centers to motoneurons via motor interneurons
- Examples: stand up from chair, wave hello
2 classifications of movement: posture and praxis
Descending tracts:
- ______ tracts correspond to posture
- _____ tracts correspond with praxis
- _____ tracts correspond with nondeliberate, emotional actions (wince in pain)
Simple vs complex movements:
Simple: ______ tracts, ____ connections to muscle
Complex: ____ tracts, _____ connections to muscle
2 classifications of movement: posture and praxis
Descending tracts:
- medial tracts correspond with posture
- lateral tracts correspond with praxis
- extrapyramidal tracts correspond with non-deliberate, emotional actions (wince with pain)
Simple vs Complex Movements:
- simple: all descending tracts, indirect connections to muscle
- Complex: corticospinal and corticobulbar tracts, direct connections to muscle
Postural Control:
Difficulty holdong a posture depends on:
1.
2.
Center of Pressure: point where gravitational force vector passing through center of mass intersects with _____
What is the goal of postural control?
Postural Control:
Difficulty of holding a posture depends on:
- Center of Mass
- Support Surface: point at which body touches the ground
Center of Pressure: point where gravitational force vector passing through the center of mass intersects with the ground
Goal of Postural Control: keep the center of force directly above the support surface
Postural Control: Standing:
Gravitational force vector in a upright human exerts a torque on ____
Standing depends on activity of a few muscles in the ankle and hip:
1.
2.
Passive _____ and active ____ allows us to stand for extended periods of time with little energy cost
Postural Control: Standing
Gravitational force vector in an upright human exerts a torque on all three joints in the leg
Standing depends on activity of a few muscles in the ankle and hip:
- Soleus
- iliopsoas muscle
Passive biomechanics and active muscular force allows us to stand for extended periods of time with little energy cost
Postural Control: Center of Mass and Support Surface
Difficulty of holding a posture depends on:
1.
2.
Explain these positions and their postural difficulty:
Lying prone
Sitting
Bipedal upright
Postural Control: Center of Mass and Support Surface
Difficulty of holding a posture depends on:
- Center of Mass
- Support Surface - point at which the body surface touches the ground
Positions and their postural difficulty:
Lying Prone: maximum support surface, easy
Sitting - intermediate support surface, middle difficult
Bipedal upright: limited support surface, difficult
We use muscular force to oppose ______ and move the center of force back to ______
We use muscular force to oppose disturbance of mass and move the center of force back to a spot overlying the support surface
Lordotic Posture: increases the ____ of the lower back and ___ upper back
Lordotic Posture: increases the concavity of the lower back and extends the upper back
Pregnant women do this
Anticipatory adjustments maintain _______ during standing and other conditions of self motion
Anticipatory adjustments maintain posture during standing and other conditions of self motion
_______ reflexes are engaged in human standing (from sitting)
The goal of postural control is what?
How does that apply when you sit up from your chair?
Feed forward reflexes are engaged in human standing
Goal of postural control is to keep the center of mass directly above the support surface
Therefore you lean forward when getting up from a chair
Anticipatory Postural Adjustments:
Commond initiating a primary action is “copied” to one or more of the ________ tracts, which in turn contact motor interneurons
Example: an action command arising from the motor cortex travels through the _______ tracts to ensure postural adjustments through signal in the ___ tract
Anticipatory Postural Adjutment:
Command initiating a primary action is copied to one or more of the descending postural tracts, which in turn contact motor interneurons
Example: an action command arising from the motor cortex travels through the lateral corticospinal tract to ensure postual adjustments through signal in the ventral corticospinal tract
Feedback circuits are engaged in response to unpredictable enviornments:
If you are on a boat with huge waves:
Descending postural tracts generate adjustments using a variety of mechanisms:
- somatosensory afferents detect conditions - eliciting ______ corrections
- Basic motor reflexes provide adjustments to ______ perturbations
- Visual and vestibular input signal for adjustments
Falling rapidly excites _______ tract neurons that increase physiological exterior activity, opposing gravity and promoting an upright posture
If you are on a boat with huge waves:
Descending postural tracts generate adjustments using a variety of mechanisms:
- somatosensory afferents detect conditions - elliciting feedback corrections
- Basic motor reflexes provide adjustments to unanticipated perturbations
- Visual and vestibular input signal for adjustments
Falling rapidly excites lateral vestibulospinal tract neurons that increase physiological exterior activity, opposing gravity and promoting an upright posture
Descending postural tracts provide a central control system that regulates the ______ and also adjusts ________, even reversing the gain of reflex to stabilize _______ and mantain ______ during self-generated movements
Descending postural tracts provide a central control system that regulates the center of force and also adjusts reflex sensitivities, even reversing the gain of reflex to stabilize posture and maintain balance during self-generated movements
Abnormal Tonic Postures:
- Decerebrate posture:
- _____ posture
- _____ lesion
- _____ of both arms and legs
- head _____ with teeth ____
- Decorticate Posture:
- _____ posture
- ____ lesion
- Foot and leg ____, elbow ____
Abnormal Tonic Postures:
- Decerebrate Posture
- extensor posture
- pons lesion
- extension of both arms and legs
- head dorsiflexed with teeth clenched
- Decorticate Posture:
- flexor posture
- midbrain lesion
- Foot and leg extension, elbow flesion and adduction
Summary of Postural Control:
- Posture maintenance difficulty depends on _____ and _____
- Feedforward circuits are engaged in ______ movements
- Feedback circuits are engaged in response to___
- Abnormal tonic postures include ____ and _____
Summary of Postural Control:
- Posture maintenance difficulty depends on center of mass and size of support surface
- Feedforward circuits are engaged in anticipatory movements
- Feedback circuits are engaged in response to unpredictable enviornment
- Abnormal tonic postures include decorticate (extensor) and decerebrate (flexor) postures
What is praxis?
What are the two pathways that connect internal thoughts of forebrain to movements produced from the brainstem and spinal cord?
Praxis= physical actions that arise from cognitive processes
The two pathways that connect internal thoughts from forebrain to movements produced by brainstem and cortex:
- Lateral corticospinal tract: actions of skeletal muscles in neck body and limbs, fine motor acts
- Corticobulbar tract: actions from face and mouth: eating, winking, speaking
Rubrospinal Tract:
It originates in the ______, then crosses at the _____ and ends in the _______
Precise function in humans is ______
It supports ____, ____, and ____
Brain lesion to the LCST may still ________ - residual functions likely depend on intact _____
Rubrospinal Tract:
Originates in the red nucleus, crosses at midline immediately at the red nucleus, and ends in the spinal cord
Precise function in humans is unknown
It supports posture, locomotion, reaching
With a Brain lesion in the LCST, pt may still stand walk and reach under certain situations - residual functions likely depend on intact RST
Extrapyramidal Pathways & Motor Control:
What are the pathways that descend and travel through the pyramids at base of medulla?
What are the pathways that descend and travel outside the pyramids at base of medulla?
What type of movements do extrapyramidal pathways generate?
Pathways that descend and travel through the pyramids at the base of the medulla : LCST and parts of corticobulbar tract
Pathways that descend and travel outside pyramids:
rubrospinal tract and others
Extrapyramidal pathways generate movements that are automatic to emotions NOT deliberate (example is smiling after a joke)
Fine Voluntary Movements:
Starts where?
Goes to where?
Ends up where?
Fine Voluntary Motor Movements:
- Cortex (primary motor, somatosensory areas) —–>
- Corticospinal and corticobular tracts——>
- Interneurons and motoneurons in the spinal chord and cranial nerve nuclei
Somatotopy:
What does somatotopy and homunculus represent?
What is most of your cortical area designated to?
Somatotopy and homulculus:
Somatotopy: the relative cortical area controlling different body parts is related to the precision with which movements of the regulated muscles are controlled
Homunculus: most of the cortical area is designated to the hands and the bottom half of the face
Fine Voluntary Movements:
- Voluntary control of the muscles on one side of the body depends on neurons in the motor cortex on the _________ side
- Within the forebrain and brainstem, lateral corticospinal axons travel _____ to the muscles they influence
- Within the spinal cord, the lateral corticospinal tract controls muscles on the _____
Fine Voluntary Movements:
- Voluntary control of the muscles on one side of the body depends on neurons in the motor cortex on the opposite/contralateral side
- Within the forebrain and the brainstem, lateral corticospinal axons travel contralaterally to the muscles they influence
- Within the spinal cord, the lateral corticospinal tract controls muscles on the same side
Corticobulbar Tract: Facial Nucleus:
Fine control of muscles in the bottom half of face is important for ____ and _____
Only in primates, the corticobulbar tract _____ innervates motorneurons that control muscles of facial expression
In the top half of the face, humans retain a pattern of predominantly _______ motor control
Corticobulbar tract innervation of facial motoneurons controlling the upper face muscles is mostly ______.
Corticobulbar Tract: Facial Nucleus:
Fine control of muscles in the bottom half of face is important for eating and speech
Only in primates, the corticobulbar tract directly innervates motorneurons that control muscles of facial expression
In the top half of the face, humans retain a pattern of predominantly indirect motor control
Corticobulbar tract innervation of facial motoneurons controlling the upper face muscles is mostly bilateral.
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