Video: Caudate nucleus level
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Hey everyone! It's Nicole from Kenhub. It's all good to learn Anatomy like this, looking inside the human body at diagrams or even dissection. But what about when you get a real, fully intact human... Read more
Hey everyone! It's Nicole from Kenhub. It's all good to learn Anatomy like this, looking inside the human body at diagrams or even dissection. But what about when you get a real, fully intact human and you need to find out what's wrong with them. Cutting them open is, of course, best avoided whenever possible. That's where medical imaging comes in, and becomes a very helpful tool for diagnosis and exploration of human anatomy. But it's a pretty different way of looking at the body. What if you were presented with an image like this? Or this?
We need to be able to identify what we're seeing in these sections in order to know how to localize what we see in these images. Today, we're going to be continuing our series on cross-sections of the human body, which is the first step into becoming an MRI or CT pro. So, let's get started just and identify structures in a cross-sectional image so we can then figure out what's wrong with these people. The level we'll be looking at is the level of the caudate nucleus.
We'll begin this tutorial by reviewing the planes of the body and identify which one we use for cross-sectional images. We'll also briefly cover what a cross-sectional image is and how to orientate ourselves when looking at them. Next, we'll look at where the caudate nucleus is so that we can anticipate what sort of structures to expect to see in the cross-sectional images at this level, and finally, we'll get into identifying these structures. We'll be looking at the bones.
After that, we'll identify the muscles at the level of the caudate nucleus, then we'll work our way through nervous structures, and finally, we'll identify any vessels that we can see. After we've identified all of the structures at the level of the caudate nucleus, we'll chat about what you might see at this level clinically.
Body planes are imaginary planes, or flat surfaces, that cut through and section the body while it's in its anatomical position. The first is the plane we can see highlighted in this image. This is the coronal plane. The coronal plane is a vertical plane that divides the body into anterior and posterior parts.
Now what we can see highlighted is another vertical plane, but this time dividing the body into left and right parts, and this is called the sagittal plane.
The third and final body plane is the transverse plane, which we can now see highlighted in green. This is a horizontal plane which divides the body into superior and inferior portions. Transverse planes are the planes that we make cross-sectional cuts in, so this is what's happened to the body when we look at cross-sectional images. And, of course, that's what we'll be focusing on in this tutorial.
In this video, we'll be looking at some structures that we can see at this level in the transverse or cross-sectional plane. These cross-sectional images are similar to what can be seen in CT and MRI scans. Just as with those scans in cross-sectional anatomy, we're looking at the images as if we're standing at the patient's feet looking superiorly towards the patient's head. Also, it should be noted that the patient is always lying on their back. Therefore, this side of the image is the right-hand side of the patient's body and this is the left-hand side. Over here, we have the anterior or the front of the body and at the bottom of the screen is the posterior aspect where the patient's back is.
So when we study cross-sections, always keep in mind the right side of the image is the left side of the body and the left side of the image is the right side of the body. So let's jump into identifying structures at the level of the caudate nucleus. Any idea what the caudate nucleus is and where we'll find it?
So, there are two caudate nuclei and they are part of the brain. Specifically, they are a component of the basal ganglia and the level that this cross-sectional image is at is superior enough that we'll be looking at structures superior to the nasal cavity and orbits. And this is the image we'll continue to look at throughout this tutorial as we identify the bones, the muscles, the nervous structures, and the vessels present at this cross-sectional level.
The first set of structures we'll identify are the bones at the level of the caudate nucleus. So at the level of the caudate nucleus, we're looking at the head, and therefore, the bones we identify will be part of the skull - specifically, the neurocranium which houses the brain.
Anteriorly is the bone that makes up your forehead, and this is the frontal bone. The frontal bone is a single bone that protects the anterior portion of the brain. Starting with this image of the left side of the skull, let's cut it sagittaly and see what we'll find. Remember, a sagittal cut divides the specimen into right and left parts.
The left part has been removed and we're left with a little bit less than half of the skull looking at the internal features from the left, and the frontal bone is still highlighted in green. Within the frontal bone is a space called the frontal sinus which is located just superior and a bit medial to your eyes. They're in fact two frontal sinuses which we can now see highlighted in the cross-sectional image - one on the left and one on the right.
There are two more bones that make up the circumference of the skull at this level, and then they're highlighted in green, and these are the parietal bones. The parietal bones - one on each side - make up a large part of the neurocranium. The two parietal bones meet in the midline of the skull, and the suture at which they meet is called the sagittal suture - and we can see this suture highlighted in green at the posterior aspect of the cross-sectional image.
There's one more suture to identify in this cross-sectional image, and we can see it highlighted on both the right and left sides of the skull, and this is the coronal suture. This suture is between the frontal bone anteriorly and the parietal bones posteriorly.
So that brings us to the end of the bony structures that we can see at the level of the caudate nucleus. We'll now move on to the muscles, and there are only a few and they're found external to the skull.
The first muscle is anterior to the frontal bone and is simply called the frontalis. This muscle raises your eyebrows, and by doing so, causes those wrinkles on your forehead. The other two muscles are superficial to the parietal bones - one on the right and one on the left - and these are the temporalis muscles. And these muscles are muscles of mastication.
So now it's time to dive into the skull and see what structures of the brain we can identify in this cross-sectional image. Let's get to it.
So what we can see highlighted next to the frontal bone is the frontal lobe of the brain. In this image on the left, we can see the frontal lobe highlighted as the most anterior part of the brain. More posteriorly are the parietal lobes. In this image on the left, we can see the right parietal lobe highlighted as the most posterior part of the brain at the level of this cross-sectional image.
And this next highlight is over a feature of the brain called the longitudinal cerebral fissure, and the longitudinal cerebral fissure is a fissure that divides the brain into its two hemispheres - the right and the left.
Here again is the caudate nucleus - remember, the caudate nucleus is part of the basal ganglia so is located deep to the frontal and parietal lobes. In this illustration on the left, the main lobes of the brain have been removed so we can see the internal structures much more clearly, and we're looking at what's left of the brain from a posterior view.
Notice here that much of the cerebellum has been removed as well and what's highlighted in green on either side are both of the caudate nuclei. The specific part of the caudate nucleus that's highlighted now is the most anterior part and otherwise known as the head of the caudate nucleus.
In this image on the left, we're looking at the brain from a posterior and superior view and much of the parietal lobes have been removed so we can see a lot more of the internal structures. Highlighted in green are the heads of the caudate nuclei which are the more anterior parts of these structures.
Next, we'll look at a couple of structures that cross the midline of the brain and these are both white matter structures, so collections of axons, and these provide a means of communication between the two hemispheres of the brain. And both of the structures we'll see in this cross-sectional image are part of the corpus callosum.
In this hemisection of the brain, we can see the full length of the corpus callosum highlighted in green and we'll see two specific parts of it in the cross-sectional image. The first part is the anterior portion of the corpus callosum and is called the genu, and in this hemisectional image of the brain, we can see the genu most anteriorly.
The second part is the posterior portion of the corpus callosum and is called the splenium. In this hemisection image of the brain, we can see the splenium most posteriorly.
The final few structures within the brain are related to the cerebral ventricular system and what we can see highlighted in this image are the left and the right lateral ventricles. In the image on the left, we can see the whole ventricular system and where it sits within the brain. The left lateral ventricle is highlighted in green, and the area that we're looking at in the cross-sectional image is approximately here.
So since we're this superior in the brain, in this image on the left, we can see the anterior horn of the lateral ventricles - and this is the structure now highlighted within the brain, again, giving us an idea of where in the brain it sits.
The final structure within the brain that we'll identify at this level is the septum pellucidum, and this structure forms the medial wall of each of the lateral ventricles. In the image on the left, we're looking at the brain from a posterior and superior view and the septum pellucidum is highlighted in green and these spaces are the anterior horns of the right and left ventricles. So we can see that the septum pellucidum is on the medial side of each of the ventricles forming that wall.
The final group of structures we'll identify at this level are the vessels we can see, and the vessels draining some parts of the brain that we've been looking at are the superior cerebral veins. These veins are highlighted in green and they drain the other parts of the superolateral and medial surfaces of the cerebral hemispheres.
The superior cerebral veins drain into the structure we can now see highlighted in green which is the superior sagittal sinus, and in this cross-sectional image, we can see the anterior and posterior parts of the superior sagittal sinus. The superior sagittal sinus is one continuous structure that begins anteriorly and travels posteriorly within the falx cerebri of the dura mater.
Okay, so now that we've identified all the structures in that cross-sectional image, let's see if we can identify what's going on in a medical image.
So, various types of medical images may be taken when patients present in an emergency room to help diagnose what's going on in their bodies, and following a head trauma, the patient could be sent in for a CT scan. So as we mentioned earlier, CT scans are transverse or cross-sectional images of the body and are viewed the same way as the cross-sectional image we've been looking at throughout this tutorial.
This is an example of what a CT scan of the head could look like in person with no injuries or abnormalities and we can see a lot of the same structures as we did in the cross-sectional images during this tutorial. So, over here, we can see the superior sagittal sinus highlighted in, and in this image, the lateral ventricles are highlighted.
So what about when someone comes in with a head injury and we need to see what's going on inside their skull? So we may get an image like this from a CT scan of someone with a head injury, so we have a black arrow and that's pointing to a collection of blood that is pushing into the brain, and after having studied cross-sections of the brain, you'll come to know that this is not normal.
So, a normal structure that we can identify in this image is the lateral ventricles here and we can also see two parts of the superior sagittal sinus here and here, and the injury we can see here is called an epidural hematoma. A hematoma is an abnormal collection of blood which we've already identified, and epidural means external to the dura mater.
So now you're an expert on cross-sections at the level of the caudate nucleus. Before I let you go, let's have a quick review of what we looked at today.
So, first, we looked at the specific cross-sectional level that we focused on throughout this tutorial - the level of the caudate nucleus - and the first group of structures we identified were the bones. First, of course, was the frontal bone, and within it, the frontal sinuses. And the other two bones at this level are the left and right parietal bones. We then identified the suture between the two parietal bones - the sagittal suture - and finally, the coronal suture was the last bony feature we identified between the parietal bones and the frontal bones.
The second group of structures we identified were the muscles. First was the frontalis anterior to the frontal bone, second were the temporalis muscles external to the parietal bones, and finally, we got into the good stuff - the nervous structures of the brain itself.
So, first, we identified the lobes starting with the frontal lobe. Then we identified the parietal lobes both left and right. We then saw the longitudinal cerebral fissure that divides the brain into left and right hemispheres. The caudate nucleus at the level of which the cross-section has been taken is the structure we identified next. We specifically saw the head of the caudate nucleus as well, and the last structure of the brain that we looked at was the corpus callosum, but two specific parts of it - firstly, the genu more anteriorly and the splenium more posteriorly.
And still within the brain, we began to identify components of its ventricular system. We saw the left and right lateral ventricles. More specifically, we could also identify the anterior horn of the lateral ventricles, and finally, we saw the septum pellucidum, which forms the medial walls of the lateral ventricles.
The final group of structures we identified in this cross-sectional image at the level of the caudate nucleus were vessels. Firstly, we saw the collapsed walls of some superior cerebral veins, and lastly, we looked at the lumen of the superior sagittal sinus. And last, but not least, we talked about why studying cross-sectional images is useful in the medical field especially when diagnosing epidural hematomas following head injuries.
And that brings us to the end of our tutorial on cross-section at the level of the caudate nucleus. Hope you enjoyed it. Thanks for joining me. Happy studying!