Muscle innervation | Muscular-skeletal system physiology | NCLEX-RN | Khan Academy

Muscle innervation | Muscular-skeletal system physiology | NCLEX-RN | Khan Academy


So there are muscles that
we control, and then there are muscles the control us. So in this video we’re
going to be talking about voluntary versus
involuntary muscle control. And then I’ll talk
about the autonomic versus the somatic
nervous systems, and we’ll jump into a few of
the subunits of those systems as well. So imagine if we had this
gentleman right here, who does not look
very impressed. We can talk about what
parts of our nervous system are responsible for
voluntary control of muscles versus those parts of
the nervous system that are responsible for
involuntary muscle control. Now, the first question that
should come to your mind is why do we have
this sort of a setup? Why is it important
to have things that are involuntarily
contracting? Well, think about
structures in our body that we don’t
actively think about. We have the heart, so we’ve
got things like cardiac muscle. We’ve also got things
like our intestines, so that’s composed
of smooth muscle. Smooth muscle is also found
lining our vessels whenever we need to vasoconstrict,
or narrow those vessels. So there’s also that
smooth muscle there. So we don’t think about whether
we need to divert blood away from our skin towards our
abdomen or towards our brain. Our body just does
that for us, and that’s muscle that’s controlled
on an involuntary basis. What about on the
flip side over here? For voluntary control, which
of the three types of muscle do you think is under
voluntary control? Well, if you said
skeletal muscle, striated skeletal muscle, you’d
be absolutely correct. So that’s how we split that up. Now, what parts of our
nervous system here do we use for voluntary
versus involuntary control? I’ll start on this side. So what we have drawn
here, this person who’s not very impressed, is
the brain as it goes down into the spinal cord. This general area is
referred to as the cortex, the cerebral cortex. And that’s part of
voluntary control of muscle. In addition to that, we’ve also
got what I can call the cord, over here, the spinal cord. And that’ll also be contributing
to voluntary control of muscles. And the way I like
to remember this is that if it’s something
that’s controlled by me, if I am the one that controls
the muscle function, then I’m going to use either
my cortex, which also happens to start with a C,
or my cord, which happens to start with a C.
So if it’s controlled by me, or if it’s voluntary,
that’s going to be the cortex or the spinal
cord that comes in handy. Now, what about if we’re talking
about involuntary control? This part that I’m going to
draw briefly that sits back here behind the spinal cord
and then goes in there, that guy is called
the brain stem. And so the brain
stem is responsible for things like if we
should have more blood go to our abdomen
instead of our skin, so if we should dilate smooth
muscle in our arterioles or if our heart
should beat faster. The brain stem
will regulate that through parasympathetic
or sympathetic mechanisms we’ll talk about in a minute. In addition to the
brain stem, there’s a structure that’s found
down here that contributes to involuntary control, but
it’s not in the spinal cord. It’s actually beside
the spinal cord, and it’s lined like a chain. So I’ll draw it like this with
these sort of cell bodies, this neuronal tissue
with cell bodies that sit outside of our central
nervous system in a chain. And so this is called
sympathetic ganglia. Well, what the heck are ganglia? It sounds like it’s
plural for something. Well, let’s define that,
sympathetic ganglia, or just a ganglion if we’re going to
use it in a singular term. A ganglion is just a
cell body or a soma of a neuron that sits outside
the brain and spinal cord. I’ll just write
brain right here. And most of these ganglia
sit besides the spinal cord. So that’s an important point,
the sympathetic ganglia that sit beside the spinal cord. And so that comes
with another trick that I’d like to
think about when I’m trying to remember which
parts of my nervous system is responsible for
involuntary control. This is stuff that’s
going on that’s beyond me. It’s beyond my control. And so if it’s
beyond me, I’m going to have to use either the brain
stem or neuronal tissue that sits beside the
spinal cord in order to be able to cause involuntary
contraction of muscle. So great. That’s voluntary versus
involuntary control.

5 Replies to “Muscle innervation | Muscular-skeletal system physiology | NCLEX-RN | Khan Academy”

  1. "who doesn't look very impressed" lmao what? hahaha idk, I'm like 13 videos into this today and that made me laugh

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