So for this spinal cord, for the dorsal part, mainly receive the sensory input, okay? The ventral part, then actually, there are a lot of those motor neuron. Actually, this is a output neuron, to control the muscle. Okay, so this one, there are some kind of axon come out from these motor neuron cell bud [FOREIGN] to control the muscle. These fibers, these purple are beta fiber. They will in the way to you, the dorsal horn, okay? This is sensory input and the dorsal horn actually divided to five layers. [FOREIGN] very clear and then this a beta fiber coming to the dorsal horn, mainly the layer four and the layer five. And then of course There'll be some, there will be a lot neurons actually inside here. We'll make the synapse with this guy and then those neurons will further relay that sensory information to the brain, okay? And there is a special branch here, take a look here, this purple neuron going to the dorsal horn. At the same time, there was, there are some bright directly go to the brain. They're quite special. So this touch information, we go to the dorsal horn. And in the same time, this touch will directly go to the brain. For example, maybe some touch signal from your toe and they will directly go to your brain. Actually, result any other synapse, okay, very direct. Of course, from here then they make a synapse with this dorsal horn neuron. And then, they will relay this information to the brain, okay? There are two pathways. Take a look another one, for example, this one. This blue one, okay, let me. So for the skin, actually there are different layers, okay. It's called, this is a epidermis. This [FOREIGN] and this bottom wire is damaged, [FOREIGN] and you can take a look. This blue one, [FOREIGN], okay? But they don't have some other structure. Is it just free ending okay? Unlike these, they have this structure here, right? But for this, no. Actually, the ending actually just free in the dermis. And this one may need to, for the temperature sensing, okay? And then, this information will relay by those route, ganglion cell to the layer one and the layer five. Yeah, layer five, one and five of the dorsal horn. There's another one. Actually, this green one. This green one then a little bit different. Also is kind of free ending, okay? It's a nerve but this called C fiber. The C fiber actually is very special. [FOREIGN], okay, and they are very small. Take a look, you can see it is the rarest thing on fiber. And this fiber carry mostly the pain information, okay? And the pain information mainly into the layer one and two. Okay, this is how to, the screen tells you what kind of signal to receive. And for this one, we also talk about the, we can sense the muscle contraction by this fiber. This is called a alpha fiber, okay. This one, owning into those muscles. And for this one, The axon quite large. This is the largest axon among this group. And also, they have the [FOREIGN], but the projection is quite different, okay. Take a look at their projection, their projection should be directed into the middle of the spinal cord or the range of of the spinal cord. As I mentioned, this region they are not for motor neuron, will control the muscle. So that means actually you have muscles, the changing of the muscle contraction. And this one, we are relating information to the motor neuron, here. And those motor neurons control the muscle. To adjust the muscle contraction, and then that means these pathways quite fast, quite direct. That's important because actually you want to maintain your composure. [FOREIGN], right, and also, because this fiber is so large, the speed of the action potential traveling along this axle will be fast. And also, because it's a high water [FOREIGN]. So their speed is the fastest among this group, okay? Some of these fiber endings will kind of surrounded this hair follicle. Some of them actually will go parallel, like this parallel of this hair follicle. And those actually are fibers actually, maybe are responsible to [FOREIGN] those information. And then, make your reflex [FOREIGN].
