WEEK 3- SCI pt2 Flashcards
motor control is part of ascending or descencing pathway
descending
motor neuron of a descending pathway, whose cell body lies in the cortex or brainstem is…
upper motor neuron
α-motoneuron, whose cell body lies in the spinal cord is ….
lower motor neuron
true or false an upper motor neurons cell bodies are located in the upper potion of teh spinal cord
false , in the cortical regions or brainstem
true or false upper motor neurons synapse directly or indirectly with lower motor neurons
true
lower motor neurons cell bodies are located in
spinal cord
which motor neuron (upper or lower) synapses with the peripheral periphery
lower
local circuit neurons (INTERNEURONS) pass information to which kind of motor neuron
lower motor neurons
motor neurons are locate din which lamina
9- motor neuron column
who is sir charles sherrington
defined stretch reflex and the motor neuron
who said this ““The final common path to muscle activation is the lower motor neuron”.
sir charles sherrington
where do alpha motor neurons have their cell bodies
in lamina 9
what is a motor unit
α-MN and the muscle fibers it innervates
1 motorneuron and the muscle fiber that innervates this unit is caleld the motor unit
true or false
a motor neuron will not innervate all the muscle fibers within a muscle but will activate a part of them
true
true or false 1 muscle is activated by many motor neurons that are spreadat different levels
true
do motor units and motor neurons vary in size?
yes
do small motor neurons innervate a large amount of muscle fibers
no a few
can a larger motor neuron innervate larger muscle fibers
yes
true or false AP in small motor unit = force produced is small
true
true or false AP in large motor unit= force produced is large
true
what can we say about the relationship betwen motor unit size and force produced by the muscle
they are proportional
how can we increase relative force produced?
temporal sumamtion
what is temporal sumamtion
AP are close to eachother ahd add to eachother
what produces greater force a single muscle twitchj or muscle that has temporal summation
temp sum
small MN inneravtes what and what is the motor unit called
small skeletal red cells
slow motor unit
slow motor unit is good for
sustained muscle contraction and upright posture
true or false slow motor units produce large forces
false , the smallest force
do slow motor units last a long time
yes
what is the motor unit called that is middle size mn (resistant to fatigue)
fast fatigue-resistant motor units
Large MN innervates and what is the motor unit called
pale muscle fibers that generate force
fast fatigable
motor units
what are fast fatigable
motor units used for
running and jumping
do fast fatiguable motor units generate little or lots of force
lots
small MN innervates skeletal red cells why are they called that
lots of hemoglobin = lots of oxygen
how does small motor units sustain force for a bery long time
lots of oxygen in the red cells
pale muscles fibers do not contain alot of what
hemoglobin
mitochondira
= using less oxygen
which motor unit doe sthis apply to
“lots of force generated for a short amount of time”
fast fatiguable motor
which motor unit doe sthis apply to
“little force generated for a long amount of time”
slow motor units
true or false small MN have small diameter
yes
true or false larghe MN have larger diamter
yes
standing require what type of motor unit
slow
running walkign requires what kind of motor unit
fast fatigue resistant
faster run gallop and jumping requires what motor unit
fast fatiguable
true or false there is only one type of motor unit you need to recruit for all activities
fasle, depending on what youre doing you will recruit either smaller, medium or bigger motor units
what are two ways you can regualte muscle force
size of motor unit
temporal sumamtion
what is “frequency of AP” of MN
how close or how far the action potential are from eachother
true or false action potentional spread apart in time will create temporal summation
false
what is temporal summation
frequent and close action potentials taht add onto eachother creating larger force
is stretch reflex monosyptactic or polysynaptic
mono
In a monosynaptic stretch reflex, what is initially stretched
the tendon
In a monosynaptic stretch reflex, the tendon streches first, then what
sensory receptor in leg extensor muscle
talk about a monosynaptic stretch reflex
!
true or false in a monosynaptic stretch reflex the flexor muscle is excited
false, the extensor is
reflexes are mediated by what
loacl circutry in teh spinal chord
alpha motor neurons innervate what kind of muscle fiber
extrafusal muscle fibers
ALEX
stretch in teh muscle is sensed by which kind of muscle fibers
intrafusal
(innervated by gamma )
sensory neurons innervate what in a monosynaptic reflex
motor neurons and local circuit neurons = interneurons
what is different about a reflexs connections
sensory neuron communiacted directly with a motor neuron
(usually tehre are interneurons present)
what innervates intrafusal muscle fibers
gamma motor neurons
why do have gamma motor neurons innervating intrafusal muscle fibers (msucle spindles)
to keep it taught so it can sense stretch
what is stretch reflex responsible for
steady level of tension in muscle = muscle tone
is steady level of tension in muscle = muscle tone voluntary or involuntary
INVOLUNTARY
Normal muscle tone:
n Assists in maintaining balance
n Spring-like qualities of muscles help to smooth movements
abnormal muscle tone :
n Stretch reflex could be hypoactive
n Stretch reflex could be hyperactive
true or false Stretch reflexes work in combination with the descending system
true
SLIDE 22!
..
true or false if a ;esion to teh brain, reflexes will stop working (upper motor neuron lesion)
false
hwo is spasticity caused
Caused by damage of the SC and/or CNS n cerebral palsy, SC injury, stroke, TBI
when is spasticity noteable
Noticeable in the first few months after the initial insult
what is the scie nce behind spasticity
Lack of inhibition from the descending pathways results in
excessive contraction of the muscles
what are the features of spastic muscles
tightness, stiffness or pull
what are treatments for spasticity (OT/PT)
to prevent muscle contractures
n stretching, passive and active movements, orthotics, exercises
what are treatments for spasticity (physical modalities)
Functional electrical stimulation (FES), ultrasound, heat, hydrotherapy
name some other treatments of spasticity
Botulinum toxin injections n Medication
Baclofen & Clozapine (GABA agonists)
n Permanent neurosurgical treatment to release contractures
rhizotomy = sensory nerve destruction
how does botox work for spasticity
blocking the signal from afferent to efferent
What happens ot the reflex in an lower motor neuron lesion
no more reflex
slide 28!!!
.
what is neuropathy
loss of axons or neurons
what is myopathyh
loss of muscle fiber
what happens in neuropathy
lose size principle = losing a motor unit essentially
less smooth recruitment
what happens in myopathy
signal will go through but less force = less miuscles
what happens in AMYOTROPHIC LATERAL SCLEROSIS
lose motor neurons in lamina 9 (neuropathy)
in als do we lose the motor neuron fast or slow
slow
is there a cure for als
no
is als a neurodegenerative disease
yes
what is als prognosis
death within 5 years
(steven hawking lived much longer though)
is tehre something genetic about als
yes
in alwhy do people die quickly with als
when it starts to affect the diagrpham = cant breathe
what is Poliomyelitis
neuropathic diease where motor neurons are lost
is Poliomyelitis viral
yes
is Poliomyelitis for children
yes
what can Poliomyelitis cause
paralysis and death
is there a vaccine for Poliomyelitis
yes
do all countries have poli vaccine
no
in neuropathic diseases can demylenation also occur ?
yes!
in which diseases do we see a demylenation of axons
MS
guillain barre
diabetes
what is MS
autoimmune disorders
that also eventually destroys neurons
what is guillain barre
Autoimmune disorder
Can be triggered by insect bite & infection
Causes weakness paralysis & pain
Peaks within 2 weeks and generally resorbs itself without lasting consequences
name a myopathic disease
Muscular Dystrophy
what is Muscular Dystrophy (MD)
Genetic disease taht affcets children with motor development delays
name a type of MD
duschene
Recessive, linked to X chromosome, leads to slow paralysis, with life expectancy at 16-30 yo
what is located in the intermediate zone
interneurons !!
true or false interneurons are located in the intermediate zone
true
long distance local circuit neurons and short distance local circuit neurons are examples of what
interneurons
what is the “science” behinf Central pattern generators
if you activate a certain pool of interneurons they will induce a pattern
what is at the basis of CPG
many types of behaviors: swimming, walking, chewing, breathing, scratching…
true or false in infancy we see alot of CPG and as we grow up we get out of these patterns
true
true or false invertebrates have evolved to using CPG to move
true
locomotion for vertebrates consists of what
All vertebrates exhibit rhythmic / cyclic movements / essential for locomotion
true or false,
movements of locomotion, swimming, walking, chewing, breathing , scrtaching only go to the brain
false , These movements rely heavily on spinal cord circuits but still do need higher cotical outputs
what do CPG control
timing and coordination of complex movements
what is neuroplasticity in spinal cord
Spinal cord circuits (CPG) can reorganize themselves after injury.
how does Spinal cord circuits (CPG) reorganize themselves after injury.
This happens through a reorganization of synapses: neurons cannot regrow but can change their number and type of dendrites.
local circuits in spinal cord are called
central pattern generators
true or false if you transect the spinal cord at the thoracic level a cat will not be able to walk on a treadmill
false, he will be = reflexive movent and pattern in the spinal cord
True or false In humans, complete spinal cord transection results in permanent paralysis.
true BUT,
- Some anecdotal evidence of weak walking patterns in complete SCI patients after sensory stimulation.
- Direct stimulation of spinal cord (e.g. FES) can evoke weak locomotion-like patterns – but not enough to support the person’s weight.
true or false in incomplete SCI, some recory is possible
true
true or false, CPGs may exist in humans as well, but their activation requires descending inputs - sensory inputs are not sufficient.
true
we need the input from our brains!!!
slide 44 david MZEE talk about it
n David Mzee made history by walking at the Wings for Life World Run start line.
n In 2023, he suffered a partial SCI in a gymnastics accident. n Combined use of electrical stimulation of the spinal cord and
physical therapy enabled men with spinal-cord injury to walk.
talk about michel roccati
n Michel Roccati became the first man with a completely severed spine to walk again.
n The electronic implants wirelessly transmit his thoughts to his legs and feet via a second implant on his spine.
what are neural interfaces
Devices that interact with the nervous system
They are electronic devices placed on the outside or inside of the brain or nervous system to record or stimulate activity – or both
true or false in the example of michjel rocaccti we are fixing the pathway between the brain and spinal cord
fasle , we are bypassing the lesion
who is incharge of neuralink
elon musk
what other diseases can use these brain computer interfaces
parkinsons
stroke
deafness
memory
