hello everybody and welcome to another neuro Anatomy talk our Focus today is going to be on identifying the central sulcus which is a key landmark in neuro Radiology we know the central cus separates the frontal and parietal loes it also separates the precentral and post Central gy the motor and sensory gy respectively now for anyone reading neuro Radiology Imaging this is a fundamental skill and I want to show you 10 different ways that you can go about confidently identifying the central sulcus now why are there 10 different ways well each one of these signs don't actually show up in every single scan and you might need to draw on multiple signs to confidently say yes this is the central suus now these signs are also summarized in a radi opedia article that I'm going to link below if you want to go check out this article now we're going to start with the first sign which is the midline suus sign if you're scrolling through an axial slice like this this a T1 weighted MRI and you scroll right up to the vertex some of these suai are going to reach the interhemispheric Fisher here you're looking for one of the suai that both intersects the inter hemispheric fure and then extends all the way down the lateral aspect of the brain and you're looking for that longest sulai that heads down towards the Sylvan fissure here in this case it's really obvious this large sulcus here is the central sulcus it intersects the interhemispheric fure here there no real large sulai that are intersecting the interhemispheric fure here now you may get another scan like this scan here if we scroll up superiorly we can see this suus intersects into hemispheric fure and so does this sulcus here if we scroll right up that's a important point you want to scroll really right up to the vertex if we were to follow this sulcus down you may follow it all the way down to the syvan Fisher we keep following it down keep following it down and you can see that it intersects the syvan fure here this isn't the central sulcus though our Central celcus is posterior to the structure if we scroll all the way up to the top we saw that this celcus intersects the inter hemispheric fure if we follow this sulcus all the way down that also heads towards the syvan fure and extends down the lateral surface of the brain notice how this sulcus as we're going down towards the Silvan Fisher it's a sulcus here sulcus here and then actually gets lost we don't intersect the silveran Fisher like the first sulcus and that actually becomes a subtle but important point to identifying the central sulcus all this to say that it's not always as obvious as our first scan here the central CK is heading down the side we may need to draw on another sign another sign we can draw in is what's known as the upper T sign if we look at the scan here we know that the central sulcus separates the parietal lobe from the frontal lobe now the frontal lobe and surface anatomy has three main sets of gy a superior frontal gyrus a middle frontal gyrus and an inferior frontal gyrus and they're separated by frontal suai a superior frontal sulkus and an inferior frontal sulcus this here represents our Superior frontal gyrus it's the most Superior the most cranial gyus of the frontal lobe and it's separated from the middle frontal gyus by this sulcus here known as the superior frontal sulcus if we follow this Superior frontal sulcus back it's going to intersect this sulcus here which is our precentral sulcus and it intersects it making an upside down T shape here you can see it's quite clear on the patient's right hand side this T marks the precentral sulcus and we know that one sulcus posterior to that is going to be the central sulcus the sulcus is named as the pre Central sulcus it's one before the central sulcus if you look on the other side it's not always as obvious here's the T sign but it's not actually intersecting that precentral sulcus in a way that we can confidently say yes this is the precentral sulcus on this side you can see how that sulcus extends out to the lateral surface of the brain it's much easier to recognize here now there's a third sign that goes along with this upper T sign and that's what's known as the L sign or the upper L sign see how the superior frontal gyrus is making up a large longitudinally orientated gyrus as that extends out posteriorly we get an uninterrupted continuation laterally with this precentral gyrus here this is what's known as the L sign we've got an inverse L sign on the patient's right hand side and on the patient's left hand side we can see that L extending out here and you can see in this scan we've got a combination of the upper T sign and the L sign here making us fairly confident that this is the central sulcus so let's move on to the fourth sign here to help us confidently identify the Central sulcus and this is what's known as the bracket sign or the pause marginalis sign or the mustache sign and I'm going to move to a different MRI that demonstrates this sign better okay so in this scan I'm going to tell you that this is the central sulcus we can head up we see it intersects the inter hemispheric fure and it extends all the way down along the side of the brain here along that lateral margin of the brain it doesn't quite intersect the syvan Fisher here see how that sulcus ends if we scroll superiorly we will see immediately there's a sulcus that makes this mustache looking or bracket looking sign here this is what's known as the pause marginalis and it's incredibly useful to identify the pause marginalis and as we extend out through one of the limbs of that bracket we know that the ccus and interior to that is going to be the central sulcus you see on this side this right hand limb anterior to that is the central sulcus it's a good way to identify where the central sulcus is now what is this pause marginalis well let's head out onto our sagittal plane we're in a mid sagital slice here we're cutting the Corpus colossum we're in that inter hemispheric fure let's scroll out laterally slightly and what we're going to see is above the Corpus colossum is this gyrus here known as the singulate gyrus above the singul gyus is the singulate sulcus it's a good Landmark to remember when you're looking at the sagittal images if we follow that singular cus round it will eventually extend superiorly towards the vertex this extension superiorly is what's known as the pause marginalis and it's this pause marginalis here that we can see on our axial slice here that's making up the bracket sign or the mustache line that pause marginalis we know we said that anterior to that the first sulcus is going to be the central sulcus so if we look at the PA marginalis we need to scroll out laterally see how the central sulcus is a bit more lateral let's scroll out laterally and we will see that the first sulcus that comes into view this is going to be our Central sulcus that Central sucus we can follow down as we scroll more and more laterally can follow it all the way down separating the frontal and parietal loes now remember I said when we follow that Central sulcus down on this axial view if we go right down here we said that that Central suus eventually disappeared prior to meeting the Sylvian Fisher and that's the basis for our next sign known as the U sign the U sign is best seen on the sagittal plane we've followed that Central sulcus down and we see it doesn't actually meet the Sylvian fissure we've got brain matter surrounding that Central sulcus and it's forming a u shape around the central sulcus this is actually a fairly sensitive way for identifying these Central Cal sulcus especially on the sagittal plane now let's follow that Central sulcus back we were following it from medial to lateral now we're going from lateral to medial as you can see here follow it all the way back and we will again see our PA marginalis come to view here's the PA marginalis now if we go back to our axial slices and scroll up to that pause marginalis this brings us to our next sign this is what's known as the bifford post Central gyus sign what happens is the pause marginalis as it extends superiorly it buys ects the post Central gyus here you can see the post Central gyus heading out towards the midline and instead of coming as a single gyrus towards the midline the pause marginalis makes these two separate gy here that helps us in identifying the post Central gyrus and we know that anterior to the post Central gyrus is going to be the central ccus again that's called the bifford post Central gyus sign let's go back to our sagittal images here we can see the par margin lanus we know that anterior to that is the central sulcus let's follow that Central sulcus laterally again out to the U sign here where we can see that Central sulcus doesn't actually intersect the syvan Fisher now anterior to the central sulcus we know is the frontal lobe and at the beginning of this talk I mentioned that the frontal lobe had a superior frontal gyrus a middle frontal gyrus and an inferior frontal gyrus now when we're looking on the sagittal images here I want to show you how you can find that inferior frontal gyrus and it's going going to bring us to our X sign the inferior frontal gyrus often has an m shape and there two sulai here an anterior sulkus and an ascending sulcus these lie inferior to the inferior frontal gyrus the gyrus above that anterior and asending sulcus is the inferior frontal Gus we can see it here if we scroll out more laterally above the inferior frontal gyus is going to be the inferior frontal sulcus remember the inferior frontal sulcus separates the inferior frontal gyrus from the middle frontal gyrus this is what's known as the lower T sign which is fitting because when we looked at the upper T sign we were separating the superior and middle frontal gyri by the superior frontal sulcus here we are separating the inferior frontal gyrus and the middle frontal gyrus by the inferior frontal sulcus and the key here is that this inferior frontal sulcus that we're following above the inferior frontal gyrus makes a t with the pre PR Central sulcus here you can see as we follow it back it intersects the precentral sulcus with this t-shape here and this is what's known as the lower T sign we had the upper T sign this is the lower T sign we know that the sulcus here is precentral sulcus one back from that is going to be the central sulcus helping us identify the precentral gyrus which is the motor gyrus if you ever have difficulty figuring out or remembering what's motor and what's sensory I like to think of it as we do things we do things motor anteriorly we feel things sensory if you're touching a stove we feel it posterior I don't know if that is useful to people but motor a lot of anatomy a lot of motor Anatomy is anterior a lot of sensory Anatomy is posterior okay let's move on to our axial slices the last three signs that we're going to look at all occur on the axial planes the first is what's known as the Thin post Central gyus sign here's our Central sulcus as we've been looking at the central sulcus separates the precentral gyus and the post Central gyus see how this post Central gyus from anterior to posterior is much thinner than the pre Central gyus that precentral gyus is thick post Central gyus is thin so if you were just to look at the gyro here and we were thinking is this a central sulcus one good question to ask yourself is is this gyrus much thinner than this gyus and that's what it is here we can see that on our other scan here as well look how thin this post Central gyrus is and how thick the precentral gyrus is the next sign is what's known as a sigmoid hook sign or the Omega sign if we look at the posterior aspect of our precentral gyus we can often get this shape for forming a large knob forming and we get an upside down Omega sign being formed on the posterior aspect of the precentral gyus that then makes this the central sulcus the one that we're trying to identify let's see if we can look at that on our other scan as well we scroll up superiorly we can see that this is the Central sulcus and here is that upside down Omega sign made by the hand Notch here or the sigmoid Notch now the last sign that I want to look at is what's known as the T1 gray white sign can become a really handy sign if you're having difficulty identifying the central sulcus now before I get into the sign I've shown you a lot of signs here to identify the central sulcus you don't need to go through this list every time you're trying to identify the central sulcus I'd encourage you pick two or three signs that are your go-to signs that you feel comfortable trying to identify the central sulcus if those don't work then you can start looking at the other signs to help you identify this is one that I like the post Central gyus is here our precentral gyus is here look at the gray white matter differentiation on the anterior surface of this precentral gyus you can identify the gray and white matter quite clearly on the posterior aspect we get lot of that gray white matter differentiation the same happens on our post Central gyrus here or the sensory gyrus there's good gray white matter differentiation on the post areia aspect but the gray white matter that abuts the central sulcus we've lost some of that differentiation this is normal within a patient and it's a good way to identify the central sulcus so there are a lot of signs that we've gone through here and as I've said pick your two or three favorites and use those predominantly when identifying the central sulcus I've chaptered this video if you want to save this video maybe to a playlist or a watch later and you ever want to re revisit these signs it's a good way to come back say what was the U sign again click on that chapter for the U sign and then you can go and revise what the U sign is so I hope that helped I hope you now feel confident identifying the central suus on an MRI until the next video goodbye everybody