Health and medicine
- What is a stroke?
- Cerebral blood supply: Part 1
- Cerebral blood supply: Part 2
- What is a stroke?
- Risk factors for stroke
- Ischemic stroke
- Hemorrhagic strokes
- Ischemic core and penumbra
- The ischemic cascade in stroke
- Blood brain barrier and vasogenic edema
- Post stroke inflammation
Cerebral blood supply: Part 2
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- Why is the brain shaped the way the brain is? Does it work best the shape it is or would it work fine in another shape?(2 votes)
- During development the brain develops gyri (ridges) and sulci (grooves) so the cortex has a hugely increased surface area compared to comparable sized smooth brain. The formation of these gyri is due to the grey matter growing at a much faster rate that the associated white matter tracts underneath while conforming to the shae of the interior of the skull.
The grey matter of the cortex is where the main processing power of the brain comes from, the more surface area, the more processing power. By wrinkling up the brain makes the most of the space it has available to grow within the skull and increase its processing power. If our brains did not have these gyri the processing power of the brain would be limited and there are actually disorders like lissencephaly which have severe consequences in terms of development, leading to early death normally.(2 votes)
- So we know that the cerebrum is primarily supplied by the anterior cerebral artery, the middle cerebral artery, and the posterior cerebral artery. So let's actually draw out on the surface of these brains here, let's draw out their supply areas, their vascular territories. So let me orient you here, so here's that side view of the brain again, looking directly from the side. And this brain here, this is just one half of the brain. So what we've done is essentially we've cut away one half of a brain. Right? And we're looking at the remaining half. >From this side. So remember we said, your anterior cerebral artery's gonna do right between these lobes, remember we said the anterior cerebral artery is here, so it's gonna serve the inside parts of the lobes, right? So your anterior cerebral artery it's gonna serve blood to the inside part of the medial part of your frontal lobe, as well as just a little bit on the outside as well. Sort of like a little bit of spillover from the blood supplying the medial part of the frontal lobe. Now your middle cerebral artery is responsible for doing a lot of the lateral part of your brain. The outside part of your brain. So it's gonna do most of the lateral part of your frontal lobe, it's gonna serve blood to it. It's gonna supply a lot of the lateral aspect of the parietal lobe. It's gonna supply a little bit of the occipital lobe, and it's gonna supply a lot of the temporal lobe, all laterally, okay? So you're not really going to see too much middle cerebral artery supply on the inside part, the medial part of your brain, except you might see a little bit, sort of a spillover at the edge of this temporal lobe, you might see a little bit right about there. And now the posterior, the posterior cerebral artery. The posterior cerebral artery's gonna do the rest of the lateral aspect of the cerebrum. So that's some of the parietal lobe, most of the occipital lobe, and a fair chunk of the temporal lobe. So that's the occipital lobe on the outside and the inside, and that bit of the temporal lobe on the outside and the inside. All right, so that's the major blood supply to the cerebrum, let's now look at the blood supply to the cerebellum. All right, so let's make the theme, our colors scheme of the cerebellar arteries, let's make it this nice little purple here, purple and pink. So the main arteries of the cerebellum are the superior cerebellar, which I'll draw in purple here, superior cerebellar. So they're actually coming off the basilar artery and wrapping backwards to reach the cerebellum. And it's really tough to see on this anterior view, but you'll just have to trust me that it's there. The next one is the anterior inferior cerebellar artery, so I'll draw that in this darker purple here, and again, that's coming off the basilar artery. You can just see how important this basilar artery is. And last we have our posterior inferior cerebellar. And that one comes off the vertebral artery and serves the bottom bit of the cerebellum. It's a little bit tough to see on the anterior view so I won't draw it in there. So those are the three major arteries of the cerebellum. See when you group them like this, I find it's a lot easier to sort of digest it all. All right, and finally we have the brain stem. So let's use green for our theme, our color scheme for the brain stem arteries. So for the brain stem we have these branches that come off the basilar artery called the pontine branches. As a group, we'll just consider them the pontine branches. And they're called the pontine branches because they serve mainly the part of the brain stem called the pons. And here they are on the anterior view. Last, we have the anterior spinal artery. Okay, so the anterior spinal artery sort of runs between it actually is connected to both the vertebral arteries and it runs down the spinal cord, the front of the spinal cord. Hence the name, anterior spinal artery. So the anterior spinal artery, even though it's called the spinal artery, it still supplies a bit of the brain stem. So all of these, everything I just showed you, these are the main blood vessels of the brain.