Now, look at this, kinda take a slice of the spinal cord for you,
this is if we're just were slicing a carrot like that and you have a little round circle,
that's exactly what you see here because the spinal cord is composed of both gray matter and white matter surrounding it.
So take a look at that graphic, look at where the gray matter is and then look at the white matter surrounding it.
Now we got some things labeled for you. You see the dorsal horn?
You see where it's clearly labeled the gray matter, all that's part of it, and the ventral horn.
So the dorsal horn and the ventral horn make up the gray matter part of the spinal cord.
The white matter is everything else around that it's kinda looks like a butterfly to me but that's what the white matter is.
Now in the white matter are these myelinated axons, okay, and the gray matter has merely the cell bodies of the axons.
Okay, so why is one called white matter and one called gray matter?
Well, they are different colors and white matter is the myelinated axons,
remember, that's the longer part; the gray matter is the cell bodies of the axon that projects the fibers up and down.
Okay, you might think like, wow, when is this gonna get fun?
You really wanna have these concepts down solid before we keep moving forward,
so pause the video for just a moment, take a little bit of time,
think about what's the difference between gray matter and the white matter.
What makes gray matter gray matter and what makes white matter white matter?
Okay, good job spending that extra time really making sure you had mastery of that before we keep moving on
because if you keep up with us in that manner where you pause and recall,
you're gonna be really surprised at how much you understand about the spinal cord.
Okay, so talking about sensory and motor tracts, fascicles or tracts are groups of neurons
that they help convey specific information about a particular area in your body.
Now we have sensory tracts and we have motor tracts.
Okay, so these tracts are just a group of neurons and they can face specific information about a particular area in your body.
We have two types -- sensory or motor. Now the sensory ones are ascending.
They convey information up to your brain so sensory goes this way.
Motor tracts are descending. They convey information from your brain to your muscles.
Okay, this is another important step.
So you know we have two types of tracts, we're talking about sensory tracts and motor tracts,
so without looking at your notes which ones ascend or move upwards? Which ones descend?
Okay, pause the video and practice that a couple of times so you have that pretty clear and solid before we move on.
Alright, I know if you are a slide counter like me, you're thinking, goodness,
if we do this after every slide, this is gonna take forever.
I promise, we're not gonna do it after every slide just the most important ones to your learning as we move forward.
Okay, so there's multiple different tracts responsible for different things.
Look at that drawing. Now we purposely don't have them labeled here,
I just want you to start to get comfortable, just kinda introduce you to the concept
that we have a lot of different tracts and each one of them has a different job or role.
And keep in mind a fascicle is just another word for tract, okay?
So look at our picture, we have all different kinds of colors there that's just to introduce you
to the topic that we have multiple different tracts and they all do different things.
Now the multiple different tracts are responsible for different things and a fascicle is just another word for tract.
Sound like we're repeating ourselves?
We are, because we know how important this is for nursing students to understand these points,
so that's why we're being meticulous about making sure this is very clear to you as we move forward.
So now you're ready to go a little deeper into sensory and motor tracts.
Now look at this, this is the gray matter organization.
Do you remember what makes gray matter gray matter? Is this mostly the axons or the cell bodies?
Cell bodies, right. Okay, now we've labeled it so let's hang out on this slide for a little while.
I want you to look at that -- look, you have dorsal horn, that's an inner neuron.
Look at the dorsal root, that's sensory, those dorsal root ganglion, follow that all the way around and take a look at those words.
So now I want you to pause the video and I want you to start from actually the dorsal horn site of the slide
and work your way all the way around counter clockwise familiarizing yourself with each one of those words.
Okay, good work. If you took the time to really work through those,
you familiarized yourself with some of the language that we use.
Now we're gonna start with a simpler graphic and I wanna talk to you about the interneurons,
remember that from the previous slide you just looked at.
Now, the SS we've got labeled there, that stands for somatic sensory neurons,
so the interneurons that we have in blue are receiving input from the somatic sensory neurons.
Now, VS, you just saw that green appear.
Those are the interneurons that are receiving inputs from the visceral sensory neurons.
Now you see that kind of yellow golden color, that's VM, the visceral motor or the autonomic neurons.
Remember autonomic means I don't have control, my body just kinda runs on its own.
And, lastly, we have SM, the somatic motor neurons.
Now remember, sensory goes which way, up or down?
Right, sensory is sending signals up; motor is sending signals down from the brain.