Central Nervous System: What It Is & How It Works

In this micro-lecture, APC Hon. Snr. Lecturer Sam Willis talks about the Central Nervous System.

In this micro lecture, we’re going to talk about the Central Nervous System.

Now the Central Nervous System is your brain and your spinal cord. Now it is a highly technical division of the body, but we want to just talk very briefly about the different parts of it. Because if you have a patient who’s developed some kind of damage to their Central Nervous System, it’s always useful to be able to know what some of the signs and symptoms are. Regardless of how complex the system is.

So as we’ve said, the Central Nervous System, the CNS, is the brain and the spinal cord. On this image here you can see the brain here, the spinal cord runs down through the spine, and then there’s the actual vertebra themselves.

So notice how each of the vertebra are given … First of all, they’re broken into sections of cervical. So they’re given a name. Then they’re given a number. So within the cervical vertebra region, there are eight cervical bones. Then the next section, which is in the middle which is the middle division, is the thoracic vertebra. And there’s 12. Finally, towards the bottom, there’s the lumbar division and there’s five lumbar vertebra.

Now not all texts consider the sacral part to be part of the system, but quite clearly here you can see it is. And the reason it clearly is, is that you can see that the vertebra nerves, the nerves are still exiting the spinal cord all the way down to S5.

So when we are considering treating our patients, we need to be mindful that if there’s an injury in one of these areas, you’re more than likely going to see different signs and symptoms depending on where the injury is.

Now just before the end of this micro lecture, I just want to show you. Over here on the right hand side. For those of you who have heard that saying before, “C3, 4, 5, keeps the diaphragm alive.” Well there’s C3, 4, 5. And absolutely you can see why it keeps the diaphragm alive. Not only do these muscles innovate the diaphragm, which is the biggest muscle of respiration, but it also controls heart rate, shoulder movements, neck movements. And that’s just between here. So this one here, this C1 to 4, covers these functions. Whereas, C4 to 6 cover heart rate.

So it’s actually C1 to 6, they’re all really, really important. I mean the reality is you could argue that all this stuff’s important. Not one part is any more important than the other.

But it gives you an idea of what you’re dealing with. And just moving down, we’ve got some of the pretty important stuff here. C7 down to T1 is hand and finger movements. Sympathetic tone, including temperature regulation and trunk stability.

And eventually all of these individual nerves, when they break off and go through … They break off, as you can see here. And they move through the vertebra. They end up in an end organ. In other words, they end in a certain part of the skin. And they are called dermatomes.

So dermatomes really is for another lecture, but as you can see, you know, T1 covers these regions and so on and so forth. So if you ever have any issues or challenges in these areas, you’re relating it to these parts of the Central Nervous System.

Okay, so that’s the micro lecture on the nervous system. I hope you found it useful. My name’s Sam Willis ( APC Hon. Snr. Lecturer) and I look forward to speaking to you again shortly.

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