hello everybody and welcome back to another anatomy tutorial today we're going to be covering the low bar and segmental anatomy of the lungs on a ct scan we're going to follow the bronchopulmonary tree through the first second and third order bronchi i'm going to show you where they course and how to name them and how they branch off within the lungs now this was something that was requested by someone in the comments below and that's a reminder if you are struggling with a specific topic post it down in the comments below and i will try my best to get a video out to you as soon as possible so let's have a look at this diagram we're going to start by looking at the right hand side of the lung then see the subtle changes that happen on the left hand side before heading on to a ct scan now a lot of people go about trying to rote learn these segments one by one or remembering some sort of mnemonic and that's not a good long term strategy those are maybe good for short term studying for an exam but it's much better to understand how they course and then not only will you be able to name the segments but you'll also be able to get a 3d awareness of where those segments are within the lungs so we have a look at this diagram we can see the trachea coming down centrally and that bifurcates into our right main bronchus and our left main bronchus on the right hand side our right main bronchus goes into our right upper low bronchus and our bronchus intermedius the right upper low bronchus then gives gives off three branches and it's best to think of this spatially as a triangle coming off we've got one section of that triangle going upwards and two going out laterally like this so we have our apical segment coming up to the apex of the lung and then we have an anterior and a posterior segment and if you think about that as at a pyramid or triangle coming out we can see the three arms of that going to the apical segment posterior and anterior segments like that then if we follow our bronchus intermedius down we have our right middle lobe bronchus coming like that and i just want to show you if you rotate this diagram around you can see that right middle lobe bronchus coming anteriorly like that and a lot of the times it's helpful when you look at the lungs to be thinking of the upper lobe as superior and then our middle and lower lobes as inferior and our middle it can almost be called our anterior lobe and our lower lobe can always be called our posterior lobe if we head across to an x-ray we can see on a lateral chest x-ray here's our upper lobe here a superior segment our middle and lower lobes are almost like an anterior and a posterior lobe the middle is not much lower or higher than the lower lobe itself and you can see why that middle lobe bronchus needs to branch off forward while our lower low bronchus heads off posteriorly another point just to remember for later and you'll see why it's important to see how the posterior portion of the lungs come much lower down than this anterior portion and when we discuss the branches later on you'll see why that is important so let's go back we've got our right middle lobe bronchus coming off and our middle lobe on the right spreads all the way around the lung peripheries so we need a medial and a lateral branch coming off that and you'll see on the lingual lobe which doesn't spread all the way around we get a superior and an inferior lobe instead here we need a medial and the lateral to get all the way around on that middle lobe then we go down into our right lower low bronchus and you'll see on both sides the first branch that comes off the lower low bronchus is this superior branch here the superior branch supplies a segment of lung that doesn't actually oppose the diaphragm it actually sits above the diaphragm like that heads out to that posterior section of the lung then our basal branches of the right lower low bronchus are our middle anterior lateral and posterior branches now i said earlier that our posterior portion of the lung goes down much more inferiorly and it goes without saying then that our posterior branch is the last branch to come off when we look on the ct scan we'll see how we can follow the middle anterior lateral and posterior branches a lot of people will remember a pneumonic here like melp m-a-l-p but given time or when you're in an exam you might be thinking of lamp or you might be thinking of palm and you're not getting those those four letters can go in many different orientations and for me i'm much more likely to remember a real word like palm than something like malp so it's better to actually understand how these arrange and remember that the post area is the last one coming off anyway let's head over to the left hand side we can see the trachea coming down dividing into our left main bronchus there and our left main bronchus gives off a left upper lobe and a left lower lobe bronchus this left upper low bronchus then gives off three branches much like the right upper low bronchus does but because we're slightly more inferior and we need to supply the lingual lobe more anteriorly here we need to send off a trunk first an apico posterior trunk here before we give off our apical and our posterior branches here and then we have an anterior branch coming forward our terminal branches are the same as on the right an apical a posterior and a lateral but here instead of our apical coming off directly we have an apical posterior before giving off our apical and posterior branches and then we have our anterior branch there then our lingual branch here comes off our left lingual bronchus gives off a superior and an inferior branch it doesn't need a medial and lateral that lingual lobe doesn't go all the way out to the periphery it just sits over that left border of the heart there and so we have a superior and inferior lingual segment here then lastly we come to our left lower lobe bronchus again it gives off a superior segment quite early on posteriorly like that and then on the left hand side we also have our four branches medial anterior lateral and posterior but on this side our medial and anterior also share a trunk so we have our anterior medial trunk giving off our medial anterior and then as we rotate around we can see how here we go our lateral and our posterior coming off on that side and we're going to see that much more clearly on the ct scan so let's head over to the ct scan so here we have an axial ct scan we've got it in the lung windows we're at the superior portion here because we can see a single trachea in the middle just posterior we can see our esophagus there what i want to do is follow that trachea down to the bifurcations let's start at the level of the corina and we get our right main bronchus and then we will see our right upper lobe bronchus coming off here we can see clearly our anterior and our posterior segments coming off and we know that there's an apical segment coming up into the screen to us so i need to scroll a little bit more superiorly to see that apical segment coming towards me let's follow that apical segment down to our right upper low bronchus anterior posterior and as we come up apical segments coming off let's follow that right main bronchus has now become our bronchus intermedius and that is going to split into our middle and lower low bronchi we saw before our middle lobe is anterior our lower lobe is posterior so we should expect a middle low bronchus coming off anteriorly here so let's follow this down keep following it down scrolling down and there we see a bronchus coming off that is our middle our right middle low bronchus and because this middle lobe extends all the way laterally here we can see it here we need a lateral and a medial branch so let's scroll down a bit more here we can see our lateral and our medial segments let's follow that back up to our bronchus intermedius we know that the posterior branch coming off there is our right lower lobe bronchus coming off so let's see our right lower low bronchus immediately almost giving off our superior segment posteriorly as you can remember from that diagram our superior segments come off posteriorly and that segment doesn't actually oppose the diaphragm itself it's not part of the basilar segments coming down there's our superior segment let's follow this even further down and we know that's going to give us four divisions our medial anterior lateral and lastly our posterior segment that furthest part down our posterior segment so there we can see our medial branch coming off our anterior branch our lateral branch and our posterior branch coming off there medial anterior lateral and posterior coming off and we can follow those down to the lung peripheries let's head our way back up to the track here we can follow on the left hand side now here's our trachea going off to our left main bronchus here and we know our left main bronchus is going to give off our left upper lobe bronchus that upper load bronchus is then going to supply the lingual branches as well as the apico posterior and anterior segments so let's follow that down here we can see it coming down and this is going to now divide into our lingula and upper sections let's now scroll superiorly so we can see those superior segments as i scroll now superiorly here we should be able to see our left upper lobe bronchus dividing into our anterior segments as well as our apico posterior trunk here which is going to divide into our posterior segment and our apical segment coming here there's our apical there's our posterior coming into the apical posterior segment and here is our anterior segment coming forward now as we scroll down we should be able to follow that back down and see the division of our lingual branches coming off here and we know our lingualer gives off our superior and our inferior segments so let's follow this further down we can see our left lower lobe bronchus follow that left lower low bronchus again posteriorly quite early on we have our superior segments on the left the same as we had on the right then if we follow that even further down we'll see our anteromedial branch our lateral branch and our posterior branch let's have a look at those we see our anterior medial branch before it bifurcates our lateral branch and our posterior branch and we can see our anterior medial branch there bifurcates into a medial and an anterior branch there there's our lateral and there's our posterior good and we can head that all the way back up and again the way to learn this is to repeat yourself go through multiple scans whenever you come across a scan with the patient go through it and follow those segments all the way down even if it's a normal scan actually especially if it's a normal scan and again i've linked this playlist down below it's a radiopaedia playlist and at the end here there's a beautifully color-coded section here showing you the various segments of the lungs and as you can see here the right upper lobe has these yellow orange and reds the middle lobes are greens and the lower lobes are blues and purples and what you can do is again follow this down right main bronchus you can see our anterior and posterior and if we scroll up superiorly we can see our superior segment and what you can do is go through this follow it see where those bronchi actually supply and you'll be amazed at how complex it looks but how well you'll be able to understand where the various segments are so i hope that helped it is a little bit of a difficult topic but if you go through this slowly systematically methodically and try and understand why the branches are named the way they are then over time this will just become second nature to you you'll be able to follow each one of those tertiary bronchi all the way out to the peripheries so as i said before let me know which videos you'd like to see me do in the future and until the next video i'll see you all goodbye