Nervous System Foundations 03 The Somatic Nervous System

What is the somatic nervous system?

The somatic nervous system is a division of the peripheral nervous system.

And its job is primarily to interface with our environment.

So the somatic nervous system is responsible for sensory information inward.

And motor control outward.

Part one,

Sensory information.

We're going to talk specifically about spinal nerves in this example.

However,

Cranial nerves are a part of the somatic nervous system.

Cranial nerves are nerves that skip the spinal cord and basically exit directly from the brain.

Spinal nerves are a part of the somatic nervous system that leave directly from the spinal cord.

And so at every segment of the spinal cord,

You have a spinal nerve that comes off and branches off into all sorts of entanglements that go and follow these big long nerves that eventually end with what we call a receptor.

A receptor is a nerve ending that detects.

.

.

Sensation from the external environment.

There are several types of receptors in the human body,

Many of which are detecting different types of sensations.

So some examples of that might be temperature.

So how warm is it?

How cold is it?

Other types might include stretch.

How much are my ligaments stretching,

My muscles stretching?

How much pressure am I getting?

Pressure is another type of receptor.

Pain is another sensory receptor.

There are different types of pain receptors.

We might see dull pain.

We might see sharp pain.

Those sensory receptors then send a message via the spinal nerve to the spinal cord up to the brain about what's happening as we interface with the world.

The brain typically will just process that information.

Grand Central Station,

As we know.

And the brain processes that information and decides what it wants to do about the information that's come in.

For the most part,

The brain just turns the volume down on most of the input that it gets.

For example,

If I put my sweater on,

I'm going to activate nerve endings that are going to tell me,

Oh,

Hey,

You've got clothing going on.

And,

You know,

For the most part,

That information arrives at the brain.

The brain's like,

OK,

Cool.

Thanks for the information.

It's not a threat.

I'm just going to turn the volume down on it,

Which is why we generally don't feel our clothes once they're on.

Sometimes what happens is maybe I wear a sweater that's really scratchy or maybe the elastic is really tight.

Then what happens is the brain doesn't turn the volume down on that until we do something about it.

So maybe it says,

Hey,

Take that sweater off,

Or maybe it's put a layer underneath that sweater.

And until we actually deal with it,

That receptor and that sensory input isn't going to go anywhere.

Or it just.

.

.

Continues to feel like not great.

You know,

Either way.

From there,

Then what happens is if that threat or that not-so-great sensation is still in existence,

We still feel it,

It might become aggravated,

It might continue to get worse,

Eventually we do something about it.

Once we've done something about it,

We've neutralized the threat.

It goes away.

Brain turns the volume down on that information.

We're all good.

Back to status quo.

Back to factory settings.

What happens when we are injured?

When we have an injury,

Let's say,

For example,

I take a tumble on my bike and I end up with a great big bruise on my leg.

Ouch.

We might have some nerve endings at that area that are now going to detect threat.

And unfortunately,

This threat is something that may have created a little bit of tissue damage.

So in this case,

I've got a great big red hot swollen bruise.

That bruise isn't going anywhere until the tissue takes its time to heal.

So in the meantime now,

These nerve endings are now going to communicate that we've had something happen to the body.

We might have pain receptors.

We might have some dull pain,

Maybe even some sharp pain.

Those sensory receptors are sending that information to the brain.

The brain's like,

Oh yeah,

Okay,

We've got pain.

We might also have some maybe pressure receptors that are picking up on the swelling.

Maybe some heat receptors are picking up the fact that we've got some inflammation here.

So now that information isn't something that the brain can just turn the volume down on.

It's like.

Oh shoot,

Now I got to do something about this.

So it might decide,

Hey,

Let's turn this group of muscles off.

Maybe the quad muscles on the front of the thigh.

Let's turn them off to prevent further tissue damage.

And then maybe the muscles on the back of the leg,

The hamstrings.

They might end up working extra hard to compensate for the quadriceps that are no longer firing in response to this tissue injury.

And,

You know,

That's actually pretty amazing that we have this nervous system that can do this to spare the tissue.

And as we know,

The body is incredible.

And what it does is it heals.

We have this amazing ability to heal and our tissue gets better and those bruises go away.

And that is so,

So,

So cool.

There was one little glitch in the system and that is that once the tissue is healed,

The nervous system doesn't always get the update.

So now what that means is these receptors,

These nerve endings on this spot that used to be bruised can continue to communicate indefinitely that there's a red hot swollen bruise there when in fact that bruise healed up,

You know,

Maybe six months,

A year,

10 years ago.

You know,

I've seen things from childhood that are still lingering in the nervous system.

It's absolutely wild.

And so.

.

.

Now what happens is after this injury,

These receptors continue to communicate that I've got a red hot swollen bruise here.

And so what the brain continues to do then is,

Okay,

Let's keep those quads off,

Keep those hamstrings working extra hard.

And then eventually,

You know,

We might not feel that it doesn't,

You know,

Maybe we feel like we're not getting a great connection there,

But it's not a big deal.

We continue to do our things and live our lives until maybe one day we have knee pain or we go to go and do something and we end up with a hamstring strain.

Because it's just been working for so long,

For so hard,

And it's just done kaput.

So how do we fix that?

There are a few things we can do about it.

And this is where really good therapy comes into play.

What is absolutely essential is that when you do go and rehab an injury,

That you address the nervous system.

That's the most important thing.

You know,

Doing massage and exercise is really,

Really important,

But we want to make sure that we're addressing the muscular imbalances and the nervous system communication that has been altered as a result of this injury.

I hope this helps.

I hope that this gives us an understanding of the somatic nervous system.

And then what can happen to it when we have an injury.

The great news is that we can heal the somatic nervous system.

There are tons of ways to include the nervous system in rehab,

And so much of it is around motor control and communication optimization.

Thanks again for watching.

Thanks a lot.