Exam 4: L1 Flashcards
Motor Systems:
What are the three levels of motor control?
The cortex can influence the spinal cord ____ or through the ____
All levels receive _____ and are modified by __ and ___
Motor Systems:
The three levels of motor control are:
- forebrain
- brainstem
- spinal cord
The cortex can influence the spinal cord directly or through the descending systems of the brainstem
All levels receive sensory inputs and are modified by basal ganglia and cerebellar activity
The Motor Hierarchy (draw it)
Explain what basal ganglia does
Explain what cerebellum does
Basal Ganglia: supressess movements, selects movements and chains them together to form a unitary action
Cerebellum: smoothes, coordinates, and sequences movement, required for motor learning
Movement can be fast and slow
Explain both and their comparative accuracy
Movement can be fast and slow:
FAST: sudden or exploding punch, LESS acurate
Slow: controlled, very accurate
Smooth Movements:
- predictable, _____ to control
- involves coordinated function of various muscles, motor commands to control for fatigue, balance, weight, usually “________”
Voluntary Movements:
depends on ______ muscles
exceptions are facial muscles, larynx, trachae, esophagus, urethra
Smooth Movements:
- predictable, easy to control
- involves coordinated function of various muscles, motor commands to control for fatigue, balance, weight, “usually taken for granted”
Voluntary Movements:
- depends on skeletal muscles
- exceptions are facial muscles, larynx, trachae, esophagus, urethra
Different types of movement function independently:
Passive movement:
- occurs without any _____
- a defecit of passive movement is felt as ____
- Lesions in basal ganglia result in ____
- Lesions in descending motor tracts (UMN) cause ______
Passive Movement:
- occurs without any neural input (when dr bends your arm during a office visit)
- a defecit of passive movement is felt as resistance to move…caused by central problems
- Lesions in basal ganglia cause rigitidy (felt as constant resistance)
- Lesions in decending motor tracts (UMN) cause spasticity (initial resistance then relative ease of movement)
Reflexes:
Reflexes are simply movements in reaction to stimuli (usually painful), unaffected by voluntary control
Explain areflexia and hyperreflexia and what area do they indicate a problem in?
Reflexes are simple movements in reaction to stimuli (usually painful) unaffected by voluntary control
Areflexia: lack of reflex, sign of lower dysfunction (motor neuron, NMJ, muscle)
Hyperreflexia: exuberant reflexes, typically results from lesions in descending motor tracts
Rigitidy is a sign of a lesion where?
Rigitidy is a sign of a lesion in the basal ganglia
Remember also that “spacisity” is a sign of a lesion in the descending motor tracts UMN
Stereotyped movement:
- semi________
- depends on _________
- rhythmic behaviors (like ____)
- postural control
Stereotyped movement:
- semiautomatic
- depends on central pattern generators
- rhythmic behaviors (example is swimming)
- postural control
Self-generated actions: may occur in a response to a stimulus, removed from _____
Give an example
Volitional actions:
- deliberate, willful
- _______ (brain area) is involved
- affects facial movements with _____ effort
- absence is called paralysis (absence of voluntary movements only is called _____)
- lesions are where?
Self-generated actions: may occur in response to a stimulus, removed from sensory inputs
Example: gazing at a painting, gasping at a story told by a friend
Volitional Actions:
- deliberate, willful
- cerebral cortex is involved
- affects facial movements with voluntary effort
- absence is called paralysis (absence of voluntary movements only is called volitional paresis), saving emotional activations
- lesions are motor cortex, cerebral hemisphere
Emotional actions:
originated for reasons that do not ______, reveal our ______
- cortex is involved
- inability to perform emotional actions but with normal volitional movement is called _____
Emotional Actions:
- originated for reasons that do not reach our conciousness, reveal our true feelings
- cortex is involved
- Emotional paresis: inability to perform emotional actions but with normal volitional movement
Definitions:
- Flaccid paraylsis: complete dysfunction in ___, ____ or ____, muscles have no ___
- Spastic Paraylsis: lesion in ______ or _____, involves hyper____
- Akinesia: lack of _____, damage to the _____(involved in late stage _____ disease)
Flaccid Paralysis: complete dysfunction in motoneuron, NMJ, or muscle, muscles have no tone
Spastic paralysis: lesion in corticospinal tract or supplementary motor area, involves hyperreflexia
Akinesia: lack of movement, damage to basal ganglia (involved in Parkinson’s disease)
The Spinal Cord:
The motor nuclei within the SC are arranged according to their function:
______ : neck and back
______: proximal muscles
______: distal muscles
Spinal motor neurons execute movement, and they are clustered in _________
The Spinal Cord:
the motor nuclei within the SC are arranged according to their function:
medial: neck and bacl
lateral medial: proximal muscles
lateral distal: distal muscles
Spinal motor neurons execute movement, and they are clustered into motor neuron pools or nuclei
Nuclei contain motorneurons and interneurons
Muscle Types:
There are three types of muscle;
slow twitch:
- generate force _____ and maintain it for ___
- require ____ to function, contain lots of myoglobin, lots of mitochondria
Fast twitch:
- generate large forces for short periods of time, tire out _____
- rely on ____ glycolysis, paler in color, less vascularized, contain _____ stores
Types of Muscle:
Slow twitch:
- generate force slowly and maintain it for a long period of time
- require oxygen to function, contain lots of myoglobin, lots of mitochondria
Fast twitch:
- genearte large forces for short periods of time
- rely on anaerobic glycolysis, paler in color, less vascularized, contain glycogen stores
Muscles are mixed in fibers
Which fiber predominates?
Muscles are mixed in fibers
Slow twitch fibers predominate
Explain the difference between these two muscles and the movements they make Orbicularis oculi (blinking):
Soleus Muscle
Orbicularis Oculi (blinking): fast twitch >>> slow twitch (burst activity), fast short lived movement
Soleus Muscle: slow twitch >>>> fast twitch
- tonic movement, ongoing for a long time, postural
The Motor Unit is the smallest division of muscle:
Define the term motor unit
Muscle control is carried out by _______
Motor pools consist of ______
Muscle control is done by _____
Motor unit is the smallest division of muscle:
Motor unit: a motor meuron and the number of fibers it innervates
Muscle control is carried out by muscle pools not motor units
Motor pools consist of the alpha motor neurons that innervate a single muscle (a typical muscle is controlled by 100 MNs)
Muscle control is done by muscle pools
Motor Unit:
A motor unit is a motor neuron and the amount of fibers it innervates
When an MU fires, ______ contracts
MU size = _______
Muscles used for finely graded movements have MUs with ____ fibers than those used for forceful contraction
All fibers of an MU are of _______
MOTOR UNIT:
A motor unit is a single motor neuron and the fibers it innervates
When an MU fires, all the fibers it connects to contract
MU size = number of fibers it innervates
Muscles used for finely graded movements have MUs with fewer fibers than those for forceful contraction
All fibers of an MU are of the same type (either all fast twitch or all slow twitch)
Henneman’s Size Principle:
Ordered recruitment of motor neurons, maximal force depends on _______
Small, slow units are active during ____ force contractions : “_____ control”
Large, fast units are active during ____ force contractions: ‘_____ control”
Henneman’s Size Priniciple:
Ordered recruitment of motor neurons, maximal force depends on the number of fibers recruited
Small, slow units are active during low force contractions: “smooth control”
Large, fast units are active during high force contractions = “poor control”
What is the advantage of the size principle?
Increased excitation to the motor pool ____ the muscle force produced
Requires _______ to control motor pool
Advantage of the size principle: It simplifies motor control
Increased excitation to the motor pool increases the muscle force produced
Requires only a limited number of axons to control motor pool (i.e corticospinal tract)
An advantage of controlling muscles via a muscle pool is compensation.
It allows for _________ even with partial loss of a motor pathway by ______ the discharge frequency of the remaining neurons
Loss in patient may not be noticed until > 50% neuronal loss has occured
An advantage of controlling muscles via a muscle pool is compensation
It allows for continued muscle function even with a partial loss of a motor pathway by increasing the discharge frequency of the remaining neurons
Loss in patient may not be noticed until >50% of neuronal loss has been reached
Muscle Denervation:
normal muscle contains Type I and type II fibers arranged in a “checkerboard pattern”
- This biochemical pattern is conferred by the motor neuron that __________
After a lesion, axon sprouting from the surviving MN creates a new histological type, causing _______ after re-innervation
Muscle Denervation:
- normal muscle contains Type I and II fibers arranged in a checkerboard pattern
- this biochemical pattern is conferred by the motor neuron that innervates each particular muscle fiber
After a lesion, axon sprouting from the surviving MN creates a new histological type, causing fiber-type grouping after reinervation
Motor Unit Diseases:
Explain which motor unit diseases come from each region:
- Soma
- Axons
- NMJs or target muscle
Motor Unit Diseases:
- Soma (motor neuron diseases)
- Axon (peripheral neuropathies)
- NMJs or target muscles (myopathy)
Explain the neurogenic disease that arises from:
Motor neuron
Peripheral Nerve
Neurogenic Diseases
Motor neuron: ALS
Peripheral Nerve: Guillan-Barre Syndrome, chronic peripheral neuropathy
What do EMGs do?
EMGs are recorded with thin needles in the muscle
Helps distinguish between problems in the muscle or higher up (MS, stroke)
EMGs measure motor unit function
