Now by now you know the central nervous system and the peripheral nervous system are the two biggest components of our quote, unquote, neural nervous systems. And in the central nervous system, we start with the top brain. Professor Chang Yen has taught you some of the anatomy but I'm going to repeat some of them, not all. Some of them are very important for us to understand movement. Okay, so this brain has several parts. The telencephalon, diencephalon cerebellum and the brain stem. Among the structures, some of them for example, cerebellum [FOREIGN] is very important to keep the balance of our body. And in the telencephalon, there are brain structures that are so important for controlling movements. Now the central nervous system continues from the brain down to the spinal cord. Okay, so our spinal cord goes down all the way to here. That is considered part of our nervous system. And the spinal cord is important for both sensing and directing our motor functions, our hands, arms, and our foot, our legs. Many of them are controlled by this process. Not only we have the central nervous system in front of brain and the spinal cord. We derive nerves from those two big structures. Therefore, in the brain, we have 12 pairs of cranial nerves. And option D, from the spinal cord, we derive many pairs of. Okay, so, and we have another one that we discussed during the break. We have visceral nervous system. [FOREIGN]. Which are divided into sympathetic and parasympathetic nervous system. To be brief, sympathetic nervous system is mainly to activate, to excite, an organ function. The heart, the kidney, the stomach, so on and so forth. And a parasympathetic serves just the opposite. They inhibit the function of that particular organ. However, in our movement class, I will omit the visceral part, okay, it is important, it also has its own movement but mainly I will focus on the top two. The peripheral nerve and the spinal nerve, the brain and spinal chord. Now I've shown you that the brain functions modularized. We've seen that human being, when he sees a word, when he hears a word, when he thinks about word and they all elicit different brain areas to be excited and to function. There are two areas that are very important for our voluntary movement. Those are in the central part. This area, and this area. Okay, we sense and we decide and we have the motor function. So if you look at that area which is in the middle, but if you look at this way, that was the side view, but if you turn this way, I mean in front of you, if you cut almost right in the middle. You can see, and you look this way. So this is a cross-section. It's actually. If you look at it this way, the cortex almost represents an inverted laying down body. This thing has a nickname called Cortical Homunculus. So from inside to outside there is your toes, your leg, your trunk, your hand, and your face and so on and so forth. Those areas are designated to sense input from those areas and they move those areas. Interestingly, if you look at this sensory cortex versus smaller cortex, they are of course almost next to each other. So the order of things is almost the same. And the area, how big the areas are, are quite consistent. Okay, now, you've probably noticed, the cortex surface is not the same as our physical surface, right. For example, our toes and our leg, in our body it's pretty big, but then the representation of them is not that big But the face is this small, and it occupies a huge area of our brain cortex. The same thing with our hand. Our feet are as big as our hands, or even bigger. But our hands occupy a much, much larger brain cortex area because we need much fine tuned action. So in our body, in the the back, our resolution is very, very coarse. But in our hand, we need this really, really, really fine-tuned resolution. And that is represented in the Cortical Homunculus, both in the sensory and motor. Because when we move our back, it's basically all or none. And in our hands, we move it really, really small, right? Okay, now, so that's very interesting. And if you look at the face, it also occupies a huge area, our lips. So that's why kissing, that movement is very, very critical in our relationship building, right? You have a huge brain area designated to sense the kiss.
