hello everybody and welcome back to another Anatomy tutorial today's video is the first in a series of videos where we're going to be identifying and examining the arterial supply to the Upper Limb now it makes sense to start at the origin of that arterial Supply the subclavian artery now I've drawn this diagram here to highlight the difference between the right subclavian artery and the left subclavian artery now we know that off the arch of our aorta has three main branches the first being a brachiocephalic trunk here now that then divides into our right subclavian artery and our right common carotid artery on the left hand side our left common carotid artery and our left subclavian artery branched directly off of that aortic Arch now I've drawn two other structures in this diagram our first rib here and our anterior scalene muscle this anterior scalene muscle comes from the cervical vertebra heading towards and attaching to this first rib now we use this first rib and this anterior scalene muscle to divide the subclavian artery into three separate parts the first part of the subclavian artery is everything before the medial border of this anterior scalene muscle so on the right hand side it's from the bifurcation to this medial border and on the left hand side part one of the subclavian artery comes from the aortic Arch all the way to the medial border of this left anterior scalene muscle the part of the subclavian that lies posterior to that anterior scalene muscle is known as our second part or part two of the subclavian artery from that lateral border all the way out to the lateral border of our first rib this is the third part of our subclavian artery now this is a front-on view this is a good view to remember when we're looking at our coronal planes scanning through a CTA of the head and neck now if we were to look from an axial view looking from the top here this is the right hand side of the patient we have our brachiocephalic trunk separating into our right common carotid artery and our right subclavian artery and we can see that anterior scalene muscle sits anterior to that subclavian artery and it divides the subclavian artery into our first part second part and then our third part ends at the lateral border of this first rib it then becomes the axillary artery now most of the branches most of the time will come from this first part of the right subclavian artery and I'm going to examine the four main branches that come off this and the best way to learn these branches is by looking at the sagittal view by cutting this right subclavian artery or the left subclavian artery in the sagittal plane and seeing where those branches come off now whenever we're looking at arterial Supply anywhere in the body there's a lot of variation generally between people and I'm going to show you in the example today two variations of the branches coming off the subclavian artery so let's cut that subclavian artery in sagittal section and look at it from the sagittal View now you'll see this looks a little complicated but these are the only arteries that we need to remember when looking at the branches of the subclavian artery now if you're studying for your part one exams the way that these questions generally get asked is either you're asked to label the subclavian artery or you asked to label one of these four main branches that come off the subclavian archery very rarely will you be shown a diagram that's pointing at one of these distal branches and ask to name it in isolation what I've seen before is you're asked to label this branch and then ask to list the branches that come off so it's really important to remember the names of these branches but when we're given one slice on an image generally we won't be asked more than to identify these main branches coming off now I've labeled these branches one two three and four and that's generally the order that those branches come off from medial to lateral on our subclavian arteries now we're going to spend some time looking at ctas and I want to get used to identifying these four main branches now the first branch that comes off the subclavian the most medial branch is the vertebral artery now our vertebral arteries are going to ascend in the neck through the transverse foramina of our cervical spine eventually joining with the contralateral virtual artery and forming the basilar artery that runs along our clivis the second branch is an inferior Branch this heads off into the thorax it's known as our internal thoracic artery a really good artery to become familiar with identifying we then have a very short trunk that comes off anteriorly from the subclavian artery here is the anterior side of our patient here's the dorsal side or the posterior side of our patient now this anterior branch is known as our thyroservical trunk now we will look at these branches later on that head off to our thyroid gland then that head off to the cervical spine and then we've got lateral branches that we will spend some time identifying there's a posterior branch that comes off generally the last branch that comes off and this is what's known as our Costo cervical Branch or our Costo cervical trunk and that has a branch heading off to the first and second rib the Costo part of our Costo cervical trunk and it's got a deep cervical artery heading off into the neck so we're going to look at A sagittal view first and identify these branches before having a look at our coronal View and in axial View and then I want to go through an arteriogram of the Upper Limb and show you how the orientation changes when we're looking at those images but before we move on let's identify these branches that we're going to look at in our coronal and axial views so anteriorly here we've got our thyroid cervical trunk now our thyroid cervical trunk gives off a more medial branch here and that bifurcates into our inferior thyroid artery which has this characteristic shape it Loops back on itself it looks like a shepherd's hook and then it sends off a small artery into the neck known as our ascending cervical artery now these lateral branches here coming off of our thyrocervical trunk are the most variable when it comes to identifying these arteries often the dorsal scapular artery or The Superficial cervical artery will come directly off of these subclavian artery so it's generally best to find those distal arteries and work our way back see where those are branching off they don't always Branch off the thyrocervical trunk so let's start by having a look at our sagittal view like this and trying to identify these four major branches on a CTA of the head and neck so here we have a sagittal CTA of the header neck we can see we're in the midline we can see our sailor here our larynx here our sinuses here our cervical spine with our C1 wrapping around the dance of our C2 all of these anatomical structures we've covered in previous talks so if any of this looks foreign to you I'd highly encourage you to go back to those talks and check them out now what I want to do is scroll out laterally until we can see some of the branches of the aorta now as we scroll out laterally we can see our aortic Arch here giving off a branch this is our left common carotid artery which we can see bifurcates into our external and internal carotid arteries and we know that if we come more laterally we'll get our left subclavian artery so this is our left subclavian artery the more lateral we go we can see our descending aorta heading down into the thorax and eventually into the abdomen so here is our left subclavian artery and we want to identify the first branch that comes off the superior aspect our vertebral artery so we can see here our vertebral artery heading off into the neck we know it will Traverse the transverse parameter of the cervical spine look at that going all the way through these transverse parameter eventually looping around into the foramen magnum heading up towards the clivast where it joins its contralateral vertebral artery and makes our basilar artery Running Up That posterior surface of the clevis there so that's our first Branch our vertebral artery coming off our left subclavian artery so let's get back to our subclavian archery and I'm going to head out more laterally and we'll see those three other branches that I mentioned earlier so here's a great slice to stop at the second branch that comes off is this inferior Branch our internal thoracic artery heading along that posterior surface of our anterior thoracic wall here then anterior to that is our thyrocervical trunk we know that our thyroid cervical trunk gives off our inferior thyroid artery our ascending cervical artery as well as those lateral branches and we'll look at all of those branches when we look at our coronal and sagittal cuts and then we can see this posterior Branch here alcosto cervical Branch giving off two branches one going to our Supreme intercostal and the other wrapping around posteriorly here and heading up into the neck our deep cervical artery you can see it heading all the way up here wraps around that transverse process there and then heads up into the neck our deep cervical artery now I often find it really useful to look at the sagittal first identify those four main branches because now when we're scrolling through our axial slices all through our coronal slices we can get an appreciation for where those branches are is it a superior branch is it an inferior Branch an anterior or a posterior Branch so let's have a look at our coronal images here now the first thing I do when looking at a coronal image is to identify the first rib and identify the anterior scalene muscle then we can divide our subclavian into its three separate parts so let's scroll anteriorly on our image here and try and identify our first strip here we can see our first rib our most Superior rib follow that rib around and you will see it wrapping anterior to this left subclavian artery here that lateral border there identifies a junction between L left subclavian artery and our left axillary artery as we head more anteriority we should see here our left anterior scalene muscle coming and attaching to that first rope you see how that anterior scalene muscle lies in front of there going in front of that left subclavian artery anything behind that anterior scalene muscle is part two of our subclavian artery and anything more medial than that is our first part of our left subclavian artery so let's find the origin of the left subclavian artery here it is coming off of the arch of the aorta now our first Big Branch that comes off superiorly is our vertebral artery we can follow that all the way up through those transverse parameter heading around wrapping into the foramen magnum here heading up joining its contralateral virtual artery forming the basilar artery at the top let's go all the way back down we've identified the first Branch then we know if we scroll more anteriorly we will see that internal thoracic artery so let's scroll anteriorly looking for an inferior Branch coming off there it is there's our internal thoracic artery heading along that posterior surface of our anterior thoracic wall here now we know we are anterior to our left subclavian artery so while we're here we know the next anterior branch is our thyrocervical trunk here is our thyrocervical trunk we can follow its branches here's the medial branches our inverothyroid artery that wraps as a Shepherd hook shape and our ascending cervical artery we can see it bifurcating here's our inferior thyroid artery and lateral to that this small artery is our ascending cervical artery let's follow that inferior thyroid artery heading into the anterior portion of the neck and then hooking you see it hooking around like that supplying the thyroid and some of the anterior neck structures there's our inferior thyroid artery if we head back we can see follow up here our ascending cervical artery heading up there it is coming down now our thyroid cervical trunk also has lateral branches as we scroll anteriorly we can see that this lateral Branch wraps around the anterior part of that anterior scalene muscle and then heads out to the peripheries here and this is our suprascapular artery that we mentioned earlier now we're going to look in the axial planes it's a lot easier to see those lateral branches and see the variations of which there is one in this image now the last major Branch coming off of these subclavian artery is our Costo cervical the posterior Branch so we need to scroll posteriorly and there is that posterior Branch our Costo cervical artery or our Costa cervical trunk that gives off our Supreme intercostal artery you can see that's thin artery going that way supplying the blood supply to the first and second ribs and then this deep cervical artery which will wrap around that transverse process here and head up into the neck our deep cervical artery let's have a look on the axial arterial phase scroll right down to the arch of the aorta now the reason I'm sticking to the left hand side is we've got all this contrast and the artifact associated with on the right hand side when we look at our last image I will show you the differences that we see on the right hand side so let's see our three major branches our brachiocephalic trunk our left common carotid artery and our left subclavian artery let's follow that left subclavian archery app and we should see the first branch that comes off of the left subclavian here is our left vertebral artery and I'm not going to follow it all the way up but we want to see that left vertebral artery entering a transverse parameter of one of the cervical spines there it is we know that that is our left vertebral artery let's go back down we know that the inferior branch of this subclavian artery here as we scroll down inferiorly that inferior branch is our internal thoracic artery and that heads along that posterior surface of our anterior thoracic wall there it is the internal thoracic or internal mammary artery let's head back up to our subclavian artery we know that the anterior branch is our thyrocervical trunk now our thyroid cervical Triumph gives off lateral branches and it gives off those medial branches the ascending cervical and the inferior thyroid artery so let's go superiorly and see those medial branches here we've got our ascending very small ascending cervical artery laterally and our inferior thyroid artery immediately let's follow that inferior thyroid artery as it wraps around medially and then we can see it hook around like that hooks into the thyroid gland there supplying blood to the thyroid the parathyroids as well as many of these anterior neck structures there is our inferior thyroid artery here is our ascending cervical artery that is bifurcated from that thyrocervical trunk let's go back down to that thyrocervical trunk we can see the lateral branches and here there's just one lateral branch that heads out to the periphery which is our suprascapular artery there so then let's go back to that thyrocervical trunk there should be a posterior Branch here's the posterior Branch we know that posterior Branch gives off our Supreme intercostal artery and if we follow it around there's our Supreme intercostal artery as we scroll up here into the neck we should see that head out posteriorly we should follow that deep cervical artery all the way up into the neck there is our deep cervical artery and later we're going to look at this superficial cervical artery that we can see lying underneath our trapezius muscle both on the left and the right hand side here deep cervical Lottery superficial cervical artery let's go back to our subclavian artery now find it there so we've got our vertebral our thyroid cervical trunk our Costo cervical trunk as well as our internal thoracic artery there now on this axial view we can identify our first rib that lateral border of the first rib identifies the junction between our subclavian and our auxiliary and we can see our anterior scalene muscle here running anterior to that subclavian artery there here is our middle scalene there's our anterior scalene and our subclavian artery intersects the two so anterior to it is our anterior scaly separating the first and the second part as well as the second and the third part of our subclavian artery now what we haven't identified is our superficial cervical artery and our dorsal scapular artery that runs along the medial border of our scapula so here we can see it running along the medial border of our scapula our dorsal scapular artery so let's try and follow that dorsal scapular artery back up into the neck here and what we can see is a dorsal scapular artery actually branches directly off of the third part of our subclavian artery this is a common variant here where the dorsal scapula comes directly off of that artery and if you notice here as we're scrolling out to that dorsal scapular artery we can see another Branch being given off here which is our superficial cervical artery if we follow that all the way around we should see that superficial cervical artery lying underneath our trapezius there there's our superficial cervical artery so in this patient our dorsal scapula and our superficial cervical actually come off the third part of the subclavian artery now I want to show you one more image and that is a CT angiogram of the entire Upper Limb now a patient sitting like this within the CT scanner so you can see how the orientation of these arteries has changed their arm is no longer on their side like this go to our axial slices now this is the right arm of the patient so we are dealing with a brachiocephalic trunk prior to the bifurcation of our right subclavian and our right internal carotid artery so let me scroll all the way up into the neck here we will see our lung Fields coming into view and we want to find the arch of the aorta here so as we scroll superiorly here are three branches of brachiocephalic trunk our left common carotid artery and our left subclavian artery now we're dealing with the right hand side here so our brachiocophag trunk should bifurcate into a right common carotid artery and our right subclavian artery here's our right subclavian artery here's our anterior scalene muscle and as we scroll out to the periphery here's our first rib which marks the end of our right subclavian artery so again let's go and identify those four branches quickly the first main branch that comes off our right subclavian artery is our right vertebral artery heading up towards those transverse foramina of our cervical spine there's our right vertebral artery inferior to that our internal thoracic artery heading down this is becoming easy now with repetition we can start to see these branches Superior and anterior to that here is our thyrocervical trunk this one is quite Superior on this patient our lateral branches heading out that way and our medial branches heading this way towards our inferior thyroid artery see how that inferior thyroid artery hooks around like that and we've got our ascending cervical artery more laterally heading up into the neck here head back down let's have a look at those lateral branches we can see them heading around one giving off our suprascapular artery and another heading off towards our superficial cervical artery here's our superficial cervical artery it's torturous we can hit it all the way around and we can see it Lies Beneath that trapezius muscle here our superficial cervical artery on this image we see that our suprascapular artery goes to the superscapular region but also gives off our dorsal scapular artery here that runs along the medial border of our scapula down here that's a slight anatomical variant our dorsal scapula is coming off this suprascapular artery here let's head our way back to that thyrocervical trunk find our subclavian artery here and the last Branch we're looking for is that posterior Branch alcosto cervical artery coming off here Costa cervical artery wraps around here gives off our Supreme intercostal artery as well as our deep cervical artery we can see how deep cervical artery wrapping around that transverse process heading into the deep regions of the neck here there is our deep cervical artery there so you can see the orientation is slightly different when the patient's got their hand raised in the CT scanner like that but if we systematically look for our vertebral artery our internal thoracic our thyrocervical and our Costo cervical trunks we can then follow those arteries throughout the head and neck now again I want to stress for your part ones knowing the anterior scalene knowing the first rib and knowing the divisions of the subclavian artery are going to be very high yield pieces of knowledge then knowing those four major branches is really useful and knowing the distal branches it's often asked in exams to name those distal branches you very rarely given a slice like this saying label this artery here because of that anatomical variation if you don't have the ability to scroll it's quite difficult to identify those arteries so it is a bit of a complicated archery many branches coming off a very small space but it's important Anatomy to know especially when going into your clinical practice now that's how clavian artery exits the thoracic cavity the thoracic Inlet before heading out into the arm now when we're dealing with a stab wound up in this apical region here in the neck we need to remember that that subclavian is often injured because it comes out of this thoracic Inlet much like the lung in the Apex here heads out of our thoracic Inlet in a really vulnerable spot when it comes to traumatic injuries and that's why this region becomes incredibly important to know the anatomy here so I hope you found that useful our next talk will be looking at the next part of this archery the auxiliary artery and its various branches as it heads out towards the Upper Limb so I'll see you all in that video goodbye everybody