The central nervous system is such a delicate part of our body that it needs a stable protection against damage and injuries. Learn what protects and surrounds it from the pressures outside of the body.
Transcript of Today’s Episode
Hello and welcome to another episode of Interactive-Biology TV where we’re making Biology fun. My name is Leslie Samuel, and in this episode, Episode 069, I’m going to be talking about the meninges of the Central Nervous System. So, let’s get right into it.
Now, the central nervous system is very delicate and needs to be protected. Speaking about delicate central nervous systems, over here to the right we have an interesting picture. This picture basically shows archaeological remains of patients of brain surgery, and they were performed by the ancient doctors of the Incan empire back in the 15th century. You can see we have some significant holes here.
In studying these archaeological remains, we are able to see that significant advances were made to where the success rate of the doctors and the surgeons that performed these surgeries was up to 90 percent. So, there’s a lot going on there, but that’s not the topic for this episode. We’re going to talk more about the meninges as opposed to the archaeological stuff.
Part of the protection is provided by the meninges. We need to protect the brain, we need to protect the spinal cord, and part of that protection is done by the meninges.
The meninges surround the central nervous system, so they go around the central nervous system, and they suspend it in a protective jacket. That protective jacket is filled with CSF. That stands for ‘cerebrospinal fluid.’
Let’s kind of try to visualize this. Here we have a picture. This is showing the brain. This part here is the brain, so this is dealing with the cortex. As you can see, we have a number of layers even before we get to the bone.
The first layer is called the, ‘pia mater,’ and then, we have the ‘arachnoid layer,’ and ‘dura mater.’ So, pia mater, arachnoid, and dura mater. A good way of remembering this from inside to out is, you have a P.A.D. that surrounds your brain: ‘P’ for pia mater; ‘A’ for arachnoid, and ‘D’ for the dura mater. And then, of course, we have the bone, the periosteum, which is the membrane that surrounds the bone, and then, we have the skin.
The three meninges– pia mater, arachnoid, and dura mater, and you can also see that over here. Here, we’re looking at the brain. So, this is the cerebrum. You can see, we have this very thin layer that’s directly connected to the brain. That is the pia mater, then, we have a space. This is called , the ‘subarachnoid space,’ but, we’re not going to go into that in this video.
Then, we have this green line that goes around here, and that thin line is the arachnoid. And then, we have a thicker band, and that is the dura mater. That’s the wider part here. So, those are the three layers, .A.D.
Let’s look at a different picture that shows the same thing here. We have this red line as the pia mater. And then, we have this space, then, we have this thin line here. That is the arachnoid, and we have the dura mater. Pia, arachnoid, and the dura.
As you can see, the dura is the thickest, then we have the arachnoid, and then, the very thin pia mater.
All right, so, if you want to look at an organizational chart, here we have the meninges, and the three types are the dura mater, arachnoid mater, and pia mater—those are the three meninges. And then, we can take the dura mater and subdivide that into the meningeal layer and the peritoneal layer.
The peritoneal layer is the layer that is attached to the bone. So, the dura mater has two layers: The meningeal layer and the peritoneal layer.
The arachnoid and pia mater, those are thin layers that we can put together and call leptomeninges. “Lepto” comes from the Greek word that means “thin or fine,” and “dura ” means tough. And, that’s why you get words like , “Durable.” Something that’s durable is very tough. The dura mater is tougher, and it’s stronger and thicker, and then, we have the two thin layers called the arachnoid and pia mater. Both of them, we can take them together and call them, ‘leptomeninges.’
That’s all I want to talk about in this video. As usual, I want to invite you to visit the website, Interactive-Biology.com for more Biology videos, other resources… We just released a new Interactive study Guide, and you can check that out. You can get all the resources at the site, to help make Biology fun.
This is Leslie Samuel. That’s it for this video, and I’ll see you in the next one.