Stretch reflex, muscle spindle physiology | alpha gamma coactivation | CNS physiology
Summary
TLDRThis educational video script delves into the stretch reflex, a fundamental topic in first-year MBBS exams. It explains the reflex's components, including the muscle spindle's sensory role, the types of nuclear back and chain fibers, and their respective static and dynamic functions. The script clarifies the monosynaptic nature of the stretch reflex, its role in maintaining muscle length through negative feedback, and the clinical significance of assessing motor system integrity. It also discusses the importance of alpha-gamma co-activation in voluntary muscle movements and the impact of gamma motor neuron activity on muscle tone and reflex sensitivity.
Takeaways
- 📚 The stretch reflex is a fundamental topic in first-year MBBS exams and is crucial for understanding muscle response mechanisms.
- 💪 The stretch reflex operates within skeletal muscles and involves a complex interaction between sensory and motor components.
- 🔍 Muscle spindles, containing nuclear bag and nuclear chain fibers, serve as the sensory receptors for the stretch reflex, detecting both static and dynamic stimuli.
- 🧬 The afferent nerve fibers, classified as Group 1A and Group 2, supply the muscle spindles and convey information about muscle length and velocity of change.
- 🌟 The stretch reflex is monosynaptic, meaning it involves a single synapse between the afferent nerve fibers and the alpha motor neurons.
- 🏋️♂️ Alpha motor neurons are responsible for contracting the extrafusal muscle fibers, which are the main contractile components of the muscle.
- 🔄 Gamma motor neurons play a key role in adjusting the sensitivity of the stretch reflex by supplying the contractile ends of the intrafusal fibers.
- ⏱️ The reaction time of the stretch reflex is between 19 to 24 milliseconds, indicating its rapid response to muscle stretch.
- 🔄 Alpha-gamma co-activation is essential for voluntary muscle movement, preventing the stretch reflex from opposing muscle contractions during movement.
- 🏥 Clinical assessment of the stretch reflex, such as the knee-jerk, is important for evaluating the integrity of the motor system in patients with paralysis.
- 🚑 Hyperactive stretch reflexes can indicate upper motor neuron lesions, as the inhibitory control over gamma motor neurons is disrupted, leading to increased sensitivity of the reflex.
Q & A
What is the stretch reflex?
-The stretch reflex, also known as the myotatic reflex, is an involuntary response that occurs when a muscle is stretched. It helps maintain muscle tone and posture by contracting the muscle back to its original length when stretched.
What are the components of the stretch reflex?
-The components of the stretch reflex include a receptor (muscle spindle), an afferent limb (sensory nerve fibers), a central nervous system processing center (spinal cord), and an efferent limb (motor neurons).
What are the two types of fibers found in the muscle spindle?
-The two types of fibers found in the muscle spindle are nuclear bag fibers and nuclear chain fibers. They serve as receptors for the stretch reflex.
What is the difference between static and dynamic nuclear back fibers?
-Static nuclear back fibers are important for detecting a static stimulus, such as maintaining muscle tone. Dynamic nuclear back fibers are important for detecting a dynamic stimulus, such as changes in muscle length during movement.
How are the muscle spindle fibers supplied by nerve fibers?
-Muscle spindle fibers are supplied by efferent nerve fibers classified as Group Ia and Group II fibers. Group Ia fibers supply both static and dynamic components of the muscle spindle, while Group II fibers supply only the static component.
What is the role of the alpha motor neuron in the stretch reflex?
-The alpha motor neuron is responsible for supplying the extrafusal muscle fibers, which are the contractile fibers of the skeletal muscle. When activated by the stretch reflex, these neurons cause the muscle to contract.
What is the role of the gamma motor neuron in the stretch reflex?
-The gamma motor neuron supplies the contractile ends of the intrafusal muscle fibers (muscle spindle). It plays a role in adjusting the sensitivity of the stretch reflex and is involved in maintaining muscle tone and posture.
What is the significance of the monosynaptic nature of the stretch reflex?
-The monosynaptic nature of the stretch reflex means it involves only one synapse between the afferent nerve fibers and the alpha motor neurons. This allows for a rapid response time, which is crucial for the reflex's function in maintaining muscle tone and posture.
What is the reaction time of the stretch reflex?
-The reaction time of the stretch reflex is between 19 to 24 milliseconds, which is the time gap between the stimulus (muscle stretch) and the response (muscle contraction).
How is the stretch reflex involved in voluntary muscle movements?
-During voluntary muscle movements, the stretch reflex is modulated by alpha-gamma co-activation. This co-activation prevents the reflex from opposing the movement and allows for smooth, controlled muscle contractions.
What is the clinical significance of the stretch reflex?
-The stretch reflex is clinically significant as it is used to assess the integrity of the motor system in patients with paralysis or other neurological disorders. Hyperactive stretch reflexes may indicate upper motor neuron lesions.
Outlines
📚 Introduction to Stretch Reflex in MBBS
The script begins by introducing the topic of stretch reflex, a crucial subject for first-year MBBS students and a favorite for multiple-choice questions (MCQs). The stretch reflex is described as a complex but essential reflex involving the skeletal muscle. The components of the stretch reflex include the muscle spindle, which acts as a sensory component, and the contractile muscle fibers known as extrafusal fibers. The script explains the role of nuclear bag and nuclear chain fibers within the muscle spindle, and how they are innervated by different types of nerve fibers (1A and 2), which are responsible for detecting both static and dynamic stimuli. The explanation also covers the afferent and efferent pathways, culminating in the activation of alpha motor neurons in the spinal cord.
🔍 Detailed Anatomy of Stretch Reflex Components
This paragraph delves deeper into the anatomy of the stretch reflex, focusing on the sensory and motor components within the skeletal muscle. It explains the function of the muscle spindle, including the nuclear bag and chain fibers, and their respective roles in detecting muscle stretch. The paragraph also discusses the gamma motor neuron, which supplies the contractile ends of the intrafusal fibers, and the distinction between the sensory and motor roles of these fibers. The summary highlights the importance of the alpha and gamma motor neurons in the reflex arc, emphasizing the monosynaptic nature of the stretch reflex and its rapid response time.
🔄 Understanding Static and Dynamic Components of Stretch Reflex
The script explains the concepts of static and dynamic components of the stretch reflex. It describes how the muscle spindle responds to changes in muscle length (static) and the rate of change in muscle length (dynamic). The static component is associated with the nuclear chain fibers, while the dynamic component involves the nuclear bag fibers. The paragraph discusses the importance of these components in proprioception and the reflex's role as a negative feedback loop to maintain muscle length. It also touches on the clinical significance of the stretch reflex, including its use in assessing motor function and the impact of gamma motor neuron activity on reflex sensitivity.
🏃♂️ Alpha Gamma Co-activation and Voluntary Movement
This section of the script explores the concept of alpha gamma co-activation, which is essential for voluntary muscle contraction and maintaining muscle tone. It explains how the activation of both alpha and gamma motor neurons prevents the stretch reflex from opposing voluntary movements. The paragraph also discusses the influence of descending tracts on gamma motor neuron activity and how this influences muscle tone and posture. The summary highlights the clinical relevance of assessing stretch reflexes, such as the knee-jerk, and the use of maneuvers like the Jendrassik technique to enhance reflex response.
🛡️ Clinical Applications and Impact of Upper Motor Neuron Lesions
The final paragraph discusses the clinical applications of the stretch reflex, particularly in assessing the integrity of the motor system in cases of paralysis. It explains the process of eliciting stretch reflexes and the significance of muscle support during assessment to prevent voluntary contraction. The script also addresses the impact of upper motor neuron lesions, which can result in hyperactive stretch reflexes due to the disruption of inhibitory control over the gamma motor neuron. Additionally, it mentions other factors that can increase gamma motor neuron activity, such as anxiety and unexpected movements, and their effect on tendon reflexes.
Mindmap
Keywords
💡Stretch Reflex
💡Skeletal Muscle
💡Muscle Spindle
💡Nuclear Bag Fibers
💡Nuclear Chain Fibers
💡Afferent Nerve Fibers
💡Alpha Motor Neuron
💡Gamma Motor Neuron
💡Alpha Gamma Co-activation
💡Monosynaptic Reflex
💡Negative Feedback Loop
Highlights
Stretch reflex is a fundamental topic in first-year MBBS exams and a favorite for MCQs.
The stretch reflex is a reflex arc involving a stimulus, receptor, afferent, efferent, and response.
The reflex operates in skeletal muscles, involving contractile muscle fibers and tendons.
Muscle spindles are the sensory component of skeletal muscles, containing nuclear bag and nuclear chain fibers.
Nuclear back fibers are receptors for the stretch reflex, with static and dynamic varieties.
Nuclear chain fibers detect only static stimuli, unlike nuclear back fibers.
Efferent nerve fibers, classified as Group Ia and II, supply the muscle spindles.
The stretch reflex involves a direct connection between afferent fibers and alpha motor neurons.
Alpha motor neurons control extrafusal muscle fibers, which are contractile.
Gamma motor neurons supply the contractile ends of intrafusal fibers.
The stretch reflex is monosynaptic, with a single synapse between afferent and alpha motor neurons.
The reflex acts as a negative feedback loop to maintain muscle length.
The reaction time of the stretch reflex is 19 to 24 milliseconds.
Central delay in the stretch reflex is 0.6 to 0.9 milliseconds, indicating a single synapse.
Alpha-gamma co-activation is essential for voluntary muscle contraction.
Gamma motor neuron activation increases the sensitivity of the stretch reflex.
The stretch reflex is clinically used to assess the motor system's integrity.
In upper motor neuron lesions, hyperactive stretch reflexes can be observed due to increased gamma motor neuron activity.
Anxiety and unexpected movements can also increase gamma motor neuron activity.
Transcripts
Hello friends today we are going to
discuss a very important topic comes in
first year mbbs exams also a very
favorite topic for mcqs as well but it
is a bit difficult one that is a stretch
reflex so let us see the fundamentals of
stretch reflex and its applications as
well
see first as the name suggests it is a
reflex and like all the reflexes it will
have a stimulus there will be receptor
afferent Center efferent and there will
be a response so what are the components
of this stretch reflex
stress reflex operates in a muscle
skeletal muscle so suppose this is a
skeletal muscle
that is the contractile component of the
skeletal muscle where there will be lot
of muscle fibers so these are the
contractile muscle fibers which will
extend from end to end of a muscle and
the ends of these muscle fibers will
continue as a tendon now all skeletal
muscles have a sensory component as well
that is the muscle spindle
so in the center of the skeletal muscle
there is a sensory component which is
the muscle spindle and it has two types
of fibers that is there is a nuclear
back fibers so this uh first one which I
drew it is like a back you see central
part it is like a bag so this is a
nuclear back fiber and then there is
nuclear chain fibers okay nuclear back
fibers and nuclear chain fibers
so these are the receptors for the
stretch reflex
now remember there are two components of
these nuclear back fibers that is static
nuclear back fibers
and dynamic nuclear back fibers so this
is the receptor for the stretch reflex
so that means
this receptor static receptor is
important for detecting a static
stimulus and dynamic receptor is
important for detecting a dynamic
stimulus and what is the stimulus
stretch is the stimulus so we'll see
what is the static and dynamic on the
other hand nuclear chain is only
detecting static stimulus okay
so what I do is a nuclear chain there is
C so C I make it as s so it becomes a
static nuclear chain is only static
nuclear back both static and dynamic
another way to remember
this b b becomes d right so nuclear bag
is static as well as dynamic now these
nuclear bargain nuclear static fibers
are supplied by efferent nerve fibers
and what are these efferent nerve fibers
there are one a fibers and there are two
fibers now
these names come from lieth's
classification of sensory nerve fibers
so 1A fibers and two fibers Supply these
nuclear bag and nuclear chain and which
one these fibers Supply one is supplies
all the fibers that is nuclear back
static Dynamic and nuclear chain static
one A A is for all right so they Supply
this central part of these
um muscle spindle both types of muscle
spindle and both static as well as
Dynamic con component on the other hand
type 2 fiber supplies only the static
component that is static component of
both nuclear back as well as nuclear
chain fibers
so that I am not going to draw but
remember here that these fibers are
actually 1A and two fibers one a fibers
are supplying all the types of fiber
static dynamic in nuclear pack as well
as nuclear chain and two fibers it is
supplying only static component of
nuclear back and nuclear chain fibers so
these are the afferents of the stretch
reflex then these afferents actually
make contact in the spinal cord so let
me just draw a spinal cord here we'll
get another neater diagram later so they
just go into the spinal cord and from
here they actually climb these form the
dorsal column of the ascending track but
one branch of these fibers goes and
makes contact with the Alpha motor
neurons right so motor neuron that is
the Bell imaginary law motor neuron
arises from the ventral root of the
spinal cord so that is why we are
bringing it to the ventral side and this
Alpha motor neuron supplies the external
fibers which are contractile right so
remember I told you before that there
are contractile muscle fibers which run
from end to end these contractile muscle
fibers are known as extra fusal muscle
fibers okay and this sensory component
that is the spindle shaped sensory
component that is known as intrafusal
muscle fibers so you see the sulfur
motor neuron is supplying the
contractile fibers it is not supplying
the sensory fibers
so sensory component is within and the
motor component the efferent is outside
to the extra fuser fibers however there
is another motor component
that is the gamma motor neuron so here
only there is roots for the gamma motor
neuron which Supply the ends of these
introfusal fibers understanding ends of
the introfusal fibers are supplied by
the gamma motor neuron so this
intrafusal fiber it is sensory in the
central part but there is motor
component it has contractile ends which
are supplied by the gamma motor neuron
so this is the basic structure of
stretch reflex let's see a neater
diagram now
so here we are showing the muscle
spindle containing nuclear back and
nuclear chain fibers and there are one a
fibers which are supplying both right
and two fibers which are supplying only
the static component
and these are going to the spinal cord
then there is Alpha motor neuron which
is supplying to extra fusel fibers which
are basically contractile and there is
gamma motor neuron which is supplying
the ends of these muscle spindles so
these muscle spindle ends are actually
contractile so these two are the
efferents
so with this basic structure now let us
move on to the actual stretch reflects
what is stretch reflex
as the name suggests stretch reflects
basically stretch is the stimulus right
then there are efferents what is the
center it is the spinal cord which go to
the spinal cord and there is activation
of the difference that is the Alpha
motor neuron only we are talking about
simple stretch reflex there is
activation of Alpha motor neuron because
as I told you afferents are making
direct contact with the Alpha motor
neuron and this is stretch causes the
activation of the Alpha motor neurons
and there is contraction
so whenever the muscle is stretched it
is leading to contraction of the muscle
so this is the simple diagram for a
stretch reflex suppose the muscle is
stretched then when the muscle is
stretched you see what will happen these
intrafusal fibers will also be stretched
along with the muscle because they they
are passive okay so with the stretch of
the muscle spindle there will be
increase in efferent activity in these
1A and two fibers and they are going to
make contact with the Alpha motor neuron
so here you see it is a single synapse
that is why stretch reflex is
monosynaptic and it is the only example
of monosynaptic reflex in body
so it directly makes contact with the
Alpha motor neuron which supplies the
extra fusel fibers and there is
contraction
so this is the simple stretch reflex
but remember we talked about the dynamic
and static components so what is that
actually what are these 1A and two
fibers carrying
see what is a static component to
suppose this is your arm okay somebody's
arm very line diagram we will draw and
it is at 90 degrees so there is a
particular length of the muscle right
suppose this arm is a stretched to this
position then the length of the muscle
is increased suppose the arm is flexed
in that case suppose it is in this
position then length of the arm is
decreased okay now when the muscle is
stretched
right suppose this position this muscle
spindle will stretch and it will carry
the information to the Alpha motor
neuron and the muscle will contract back
again to its original length
similarly when the muscle is flexed okay
that means for flexing there will be
shortening of the muscle then this
afferent activity is going to decrease
why it is going to decrease because when
the muscle is shortening
along with that this introfusal fiber
length is also going to shorten here we
are talking about
whenever the muscle length is decreasing
the interfucer fiber is shortening we
will talk about voluntary contraction
little later that why we are able to
voluntary Flex the muscle why it doesn't
happen okay
anyways so when there is decrease in the
length of the muscle this will shorten
the muscle spindle and this efferent
activity in these fibers is going to
decrease okay and when this decreases
what will happen here the activation of
the Alpha motor neuron is also going to
decrease
thus causing decreased activation of
this extra fusel muscle fibers so there
will be relaxation and hence the muscle
will come back to its original position
so stretch reflexes working both ways
increase in the stretch is causing
contraction decrease in the stretch is
causing relaxation okay
so this is very simple you should
remember so basically this stretch
reflex is acting as a negative feedback
loop where it is maintaining the length
of the muscle Okay negative feedback
loop
but till now we are talking about static
stretch only see I told you that suppose
this is the muscle position but I never
talked about the dynamic component what
is dynamic component Dynamic component
is rate of the movement how fast the
muscle length is being changed from this
particular length through this
particular length so how fast the muscle
is being moved similarly here how fast
the muscle is being moved that is the
dynamic component and that information
is being carried by our 1A fibers
so basically two fibers are mainly for
the static length that currently what is
the length of the muscle and 1A fibers
is talking about the velocity of change
in the length of the muscle from one
position to other when it is going how
fast it is going so that information is
also very important because it kind of
tells the brain an anticipatory
information that how fast the correction
should be done also so that is the
meaning of static and dynamic component
now we have talked about the static and
dynamic component of the afference but
uh one thing more you remember here that
even the gamma motor neuron which are
supplying the contractile ends of these
introfusal fibers they are also of two
types that is the static and dynamic
okay so there also because this
information is going to the Alpha motor
neuron also to the top to the brain also
it is going so to make Corrections
later we will see that how voluntary
contraction this gamma motor neuron is
also activated so for that also we need
a static and dynamic component
so with this let us see certain facts
about stretch reflex one that this
stretch of the muscle when it causes a
stretch of the muscle spindle that is
known as loading of the spindle so
sometimes you should remember a loading
of the spindle stretch of the spindle is
known as loading of the spindle because
it is increasing the efferent activity
on the other hand the decrease in length
of the muscle
unloads the spindle so that is known as
unloading of spindle so that is one
second
the reaction panel for this stretch
reflex is 19 to 24 milliseconds what is
the reaction time meaning of reaction
time reaction time is basically time gap
between the stimulus and the response
right so from the time the muscle is a
stretched till the time the muscle is
contracted by the Alpha motor neuron
that is the total time taken for the
reflex so that is known as reaction time
and it is 19 to 24 milliseconds
now what is the importance of this 19 to
24 milliseconds when you see for any
negative feedback loop there is some
time involved why because there will be
some time in the activation of the
reference then carrying of this
information to the spinal cord some
conduction velocity this fiber will be
having so sometime it will take to
travel from one portion to the spinal
cord then
there will be some component involved in
this release of the neurotransmitters
activation of the Alpha motor neuron and
then there will be again velocity of
this Alpha motor neuron for getting the
information reaching the information to
the extra extra fusel a muscle fibers
right
so this is the entire time required for
the reflex but if we subtract the time
taken for traveling of the impulse then
we can get to know that how much time
this particular reflex is taking at the
level of the spinal cord and that is
known as Central delay and this Central
delay is found to be 0.6 to 0.9
milliseconds that means out of this 19
to 24 milliseconds only 0.6 to 0.9
millisecond time
is within the spinal cord rest all the
time is taken for conduction of the
impulse from the muscle spindle to the
spinal cord and again bringing the
impulse from the Alpha motor neuron to
the muscle
so this is the central delay again what
is the importance of this C
minimum time for synaptic delay what is
synaptic delay synaptic delay is
basically the time taken for the
neurotransmission in one synapse the
vesicles have to be released the
neurotransmitter has to act on the nerve
terminal so it is a chemical response
and because of this there is some
synaptic delay and that minimum delay is
0.5 milliseconds so if we know that this
is the minimum delay that means in this
stretch reflex there can be only one
synapse if there are two synapse how
much will be the delay it will be
greater than at least one millisecond
isn't it here we are talking that the
central delay is only 0.6 to 0.9
millisecond Which is less than one
millisecond so the number of synapses
involved in stretch reflexes single only
so that is why it is a monosynaptic
reflex I mean that's how we found out
that a stretch reflexes a monosynaptic
reflex by determining the total time
required for a stretch reflex and the
central delay
okay now let's move on to the next
component of stretch reflex that is
Alpha Gamma co-activation
now you see I gave you that example that
suppose this is the muscle length and if
it is changed to a different uh length
or different position
see when the muscle position is changed
when the arm is moved what will happen
the muscle length will also change so
basically lengthen the position are kind
of synonymous that is why these 1A and
two fibers are important for
proprioception they give the information
about the position of the arm anyways so
I told you that as the muscle length
will change this stretch reflex will
tend to bring the muscle back to its
original length right so if this happens
every time we move our arm we will never
be able to move because there is a
reflex operating it will always bring
the arm back to its original position
so how to move voluntarily well this is
because of Alpha Gamma co-activation
every time we wish to contract the
muscle there is Alpha Gamma
co-activation and every time we have to
relax the muscle there is Alpha Gamma
co-inhibition
so we use the word co-activation for the
contraction which is happening so what
is that I will just to redraw the
diagram quickly
so this is suppose extra fusel muscle
fiber and this is the intra-fuzer muscle
fiber and it is having the contractile
ends right so when we want to contract
the muscle
what we do from the spinal cord there is
basically information to both Alpha
motor neuron
and also to gamma motor neuron so both
get excited together that is the term
Alpha Gamma co-activation so what
happens because of this
see when the Alpha motor neuron will be
activated there will be shortening of
the muscle right now as I told you
before if the muscle shortens there will
be passive shortening of the introfusal
muscle fiber also stretch reflex will be
activated no with Alpha Gamma
co-activation it doesn't happen like
that because when gamma motor neuron
gets excited and it contracts the ends
of these introfusal fibers what happens
if the contractile ends contract right
then there will be stretch of this
intrafusal muscle fiber so it will
become something like this so instead of
Contracting because of the ends
Contracting there will be stretch of the
intrafusal muscle fiber so it is like
when the extra fusel muscle fibers
shorten or contract the intrafusal
muscle fibers are kept stretched they
are not allowed to shorten by activation
of the karma motor neuron so that is why
for voluntary contraction there is Alpha
Gamma co-activation
so that is one application of Alpha
Gamma co-activation in body there is
another one also
see there are many top fibers which are
affecting the activity of gamma motor
neuron
like there is a pontine reticulospinal
tract which is stimulating this gamma
motor neuron and there is medullary
reticular spinal tract which is
inhibiting this gamma motor neuron
now suppose if the muscle is stretched
and also there is I mean suppose if the
muscle is stretched there is a
particular position in which it is
maintained suppose somebody is standing
the length of the
um leg muscles will be
some value right so length of the muscle
or the position of the muscle is some
value now if during that time the
spontane reticular spinal tract
stimulates this gamma motor neuron what
will happen
in that particular length only there
will be increased stretch of the
centrifugal muscle fiber and with that
stretch what will happen that there will
be increased activation of the Alpha
motor neuron and there will be increased
contraction of the extra Fusion muscle
fibers understanding
so basically it is increasing the tone
of the muscle in a particular length
only so this gamma motor neuron
activation what we say is increasing the
sensitivity of stretch reflex okay
increasing the sensitivity of stretch
reflex for a particular position also so
that is how the various descending
tracks actually influence the activity
of gamma motor neuron to maintain muscle
tone and posture
so that is the second application of
this Kama motor neuron
third
see this stretch reflex basically is
used clinically
in assessing the motor system so suppose
in a patient of paralysis we need to
assess the Integrity of this reflex arc
and that is done by assessing various
jerks in body jerks means this stretch
reflex that is the knee-jerk biceps drug
triceps so all these reflexes we assess
at the level of the muscle and what we
say in that it has to be supported the
muscle has to be supported why we say
because we don't want the voluntary
contraction there we don't want that
Alpha Gamma co-activation to be together
there right because we are assessing
only the stretch reflex
so that that time we hit actually the
muscle on the tendon and by hitting the
muscle on the tendon we are actually
stretching this intra-fugal muscle fiber
now sometimes it becomes difficult to
elicit this stretch reflect in that case
we ask the subject to do Chandra 6
maneuver so General six man over what
happens that there is increased
activation of this gamma motor neuron
thus increasing the sensitivity of the
stretch reflex and then only we are able
to elicit this stretch reflex
so that is another importance of only
gamma motor neuron Alpha Gamma
co-activation for voluntary
contraction of the muscle then gamma
motor neuron activation increases
sensitivity of stretch reflex generous 6
manova again increases gamma motor
neuron activity so that increased
sensitivity of the stretch reflex occurs
then there is another effect on this
gamma motor neuron suppose in case of
upper motor neuron lesions in upper
motor neuron lesions what we get we get
hyperactive stretch reflex
why is it happening because the negative
influences on the gamma motor neuron get
disrupted so this gamma motor neuron
which is generally under more inhibitory
control from the upper motor neuron that
gets interrupted and that releases the
gamma motor neuron activity and it
becomes more active causing increased
sensitivity of the stretch reflex that
is why we get hyperactive
stretch reflexes in case of upper motor
neuron lesion
then there are some other factors which
also increases gamma motor neuron
activity and these are like anxiety
unexpected movements all these also
increase gamma motor neuron activity
that is why an anxiety also we get
hyperactive tendon reflexes tendon
reflexes again another term for stretch
reflex jerks okay
so that was all about the stretch reflex
hope you have understood the concept
thoroughly thanks for watching the video
if you liked it do press the like button
share the video with others and don't
forget to subscribe to the channel
physiology open thank you
Ver Más Videos Relacionados
Het bewegingsapparaat: Inleiding in de skeletspieren
What is the Stretch Reflex or Myotatic Reflex?
Brain stem
What is stretch mediated hypertrophy and why it is not going to make you Hulk level massive
BAB 2 Sistem Koordinasi Manusia || Sistem Saraf Manusia || IPA SMP/MTs Kelas 9 Kurikulum Merdeka
The Cerebellum
5.0 / 5 (0 votes)