0:00 In this video we're going to look at the anatomy of the brain, we're going to 0:08 first 0:09 look at the basic anatomy, really simple, and then we'll look at the arterial 0:15 supply, 0:16 blood supply to the brain. 0:18 So here we're looking at the lateral view of the brain. 0:21 The cerebral hemispheres originates from the telencephalon, this is embryology. 0:26 We have four main lobes, the frontal, parietal, temporal, and occipital. 0:32 Then you have the cerebellum, which is part of the metencephalon. 0:35 The pons is also part of the metencephalon. 0:39 And again, the telencephalon and metencephalon are just terminology names used 0:47 to explain 0:48 where these structures originate in terms of embryology. 0:53 Now let us look at a sagittal section of the brain and see what anatomical 0:58 structures are 0:59 important to note. 1:00 So remember this was a telencephalon, which was your cerebral cortexes. 1:06 Then you have the cerebellum, which is your metencephalon, together with your p 1:09 ons, remember? 1:11 The brain stem is made up of three sections. 1:13 From the top to the bottom is the midbrain, the pons, and the medulla oblongata 1:20 . 1:20 In the center here of the cut brain, there is the thalamus, the relay station 1:25 of the 1:26 brain. 1:27 Below the thalamus is the hypothalamus, hypo, as in below. 1:31 So hypothalamus, below the thalamus. 1:36 And below the hypothalamus, there are two lobes and these are known as the pit 1:40 uitary lobes. 1:42 The hypothalamus and the pituitary lobes, or glands, are important endocrine 1:48 glands. 1:49 Now let us look at the brain from an inferior view. 1:53 So the inferior view of the brain, you can see the telencephalon, your cerebral 1:57 cortex. 1:57 And you can see the frontal lobe here and the temporal lobes on the sides. 2:02 Then your brain stem, which is made up of your midbrain, your pons, and your 2:06 medulla oblongata. 2:08 This is your cerebellum. 2:10 Some other important structures which can be seen from here are your optic 2:16 nerves, which 2:17 is cranial nerve number two. 2:20 And this sort of branches off the optic chiasm. 2:25 And under these structures, you can find the long olfactory nerve, which is 2:30 your cranial 2:31 nerve number one, which is your smelling nerve. 2:34 It is a sensory nerve. 2:36 Okay, let us look at the same view of the brain again, but this time look at 2:42 the arterial 2:43 supply of the brain. 2:46 So crawling up the brain stem, you have the vertebral arteries, two of them 2:50 which come 2:51 from the subclavian artery. 2:53 These vertebral arteries join to form the bacilla artery, and the bacilla 3:00 arteries continue 3:02 to crawl up the brain stem, up the pons and midbrain before basically bifurc 3:10 ating. 3:11 But this bifurcation will form a circle around this region. 3:16 This circle is known as the circle of willis. 3:21 The circle of willis gives off a few branches, the posterior cerebral, the 3:27 middle cerebral, 3:28 and the anterior cerebral artery. 3:32 Joining the anterior cerebral arteries is the anterior communicating artery 3:38 because it's 3:38 a communication between the anterior cerebral arteries. 3:43 And joining the middle and posterior cerebral arteries is the posterior 3:49 communicating arteries. 3:51 There are another two important arteries that help form the circle of willis. 3:56 And these are the internal carotid arteries, which are branches of the common 4:00 carotid artery. 4:04 The middle cerebral artery is actually a branch of the internal carotid. 4:08 The internal carotid does not give off any branches during its track from the 4:15 essentially 4:16 chest to the brain, middle of the brain. 4:22 Let us now look at the circle of willis again, but separately from the brain, 4:26 just by itself. 4:28 Again here are your vertebral arteries which form the bacilla artery from the 4:31 back of the 4:32 brain, and it will crawl up the brain stem and then branch to give rise 4:37 essentially to 4:38 the circle of willis together with the internal carotid. 4:41 But essentially the bacilla arteries branch, they bifurcate giving off the 4:47 posterior cerebral, 4:48 then you have the middle cerebral, which supplies the center of the brain. 4:53 And here you have the anterior cerebral artery, which supplies the front of the 4:59 brain. 4:59 The anterior cerebral are connected to each other by the anterior communicating 5:05 artery. 5:05 And here is your posterior communicating artery. 5:09 The internal carotid artery comes from, comes straight here and joins to the 5:15 circle of willis. 5:17 And that is your circle of willis, the round structure, and it has variations 5:23 of course. 5:24 And these are the main arteries found in the circle of willis. 5:28 Now let us use this information we just learned about the cerebral arteries and 5:33 talk about 5:34 some clinical stuff. 5:36 So stroke is a serious condition. 5:40 Stroke is where we have interruption of blood flow to the brain, or the brain 5:45 stem for more 5:45 than 24 hours. 5:48 There's a terminology known as transit ischemic attack, TIA. 5:52 And this is essentially when we have interruption of blood flow to the brain 5:56 less than 24 hours. 5:58 Stroke and TIA are life-threatening. 6:02 A CT scan has to be conducted as soon as possible to distinguish between two 6:07 types of stroke, 6:09 hemorrhagic and ischemic stroke. 6:12 If it's an ischemic stroke, thrombolytic therapy has to be initiated as soon as 6:18 possible. 6:18 Now let's talk about these two types of strokes, ischemic stroke and hemorrh 6:23 agic stroke. 6:24 Here I'm cutting a coronal section of the brain. 6:26 In red are your cerebral arteries. 6:30 Here is your middle cerebral artery we're zooming into, and this is your 6:33 internal carotid that 6:35 joins to the circle of willis, forms the circle of willis. 6:38 Let's first talk about ischemic stroke. 6:43 So ischemic stroke an example of ischemic stroke is where we have plaque, where 6:48 we have a plaque 6:49 formation in the internal carotid, which can lead to a potential stroke. 6:54 Or the plaque can you know, it can rupture. 6:57 It can rupture creating a thrombus. 7:00 Thrombus results in an emboli. 7:02 The emboli then will travel up to the brain. 7:06 And remember this is the internal carotid, so the internal carotid will travel 7:10 up to the 7:10 brain to the circle of willis and actually go to the middle cerebral artery, 7:15 because the 7:15 internal carotid is the main, it forms essentially the middle cerebral artery. 7:20 So here we have the emboli, and the emboli thrombus lodges in the cerebral 7:27 artery, resulting 7:29 in ischemic stroke. 7:34 The second type of stroke is the hemorrhagic stroke. 7:37 Hemorrhagic stroke, a hemorrhage, is essentially when we have the rupturing of 7:40 the vessel blood 7:41 spilling everywhere. 7:43 So zooming into this middle cerebral artery, we have the rupture of the vessel, 7:48 because 7:49 for example, the vessel has an aneurysm, and it just grows until it ruptures. 7:56 So that is hemorrhagic stroke. 7:59 Hemorrhagic stroke usually occurs in the anterior cerebral communicating 8:03 arteries, posterior 8:04 cerebral communicating arteries, and branches of the middle cerebral and bas 8:11 ilar arteries. 8:12 So that was just a quick overview on the stroke. 8:16 Thank you for watching. 8:17 I hope you enjoyed this video. 8:18 Bye.
