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Overview of the main arteries of the circulatory system.
Hey everyone! It's Nicole from Kenhub, and in this tutorial, we'll be looking at the arteries of the cardiovascular system.
The cardiovascular system is one of the several systems in our bodies and its special role is to transport blood around the body so that it can reach each and every cell. The blood carries everything from oxygen for respiration, nutrients and waste products that need to be cleared in order for everything to function properly so it's fairly obvious why the system is so vital. The cardiovascular system comprises of the heart which, of course, pumps the blood and gets it moving and the blood vessels that transport blood to and from the heart around the body.
Now there are a couple of types of vessels. Firstly, the vessels that carry oxygen-rich blood from the heart to the rest of the body are called the arteries and the blood vessels that carry deoxygenated blood from different parts of the body back to the heart are the veins. And, of course, in this tutorial, we'll be focusing on the major arteries of the cardiovascular system and if you'd like to know more about the veins, be sure to check in at kenhub.com and have a look around to see what other resources we have for you.
Before we get into specifics, I just want to give you some general information about the arteries themselves as this can help us to understand how to identify them from other vessels. So first off, let's talk about the location of the arteries. And the arteries tend to be located deep in the body and, unlike the veins, aligned with a layer of smooth muscle. And this layer is important as it helps keep the blood moving through the body efficiently. And arteries are also tough enough to withstand changes in the blood pressure caused by the pulse.
Now that we're finished talking about the location of the arteries, I want to give you a brief overview of what we're going to be talking about today. and in this tutorial, we're going to be talking through the major arteries of the thorax followed by the arteries that are located in the head and neck followed by the arteries of the upper limbs and then we're going to follow that by talking about the arteries of the abdomen and the pelvis and then finally, we're going to talk about the arteries of the lower limbs.
So without further ado, let's jump right in as promised to introduce some of the major arteries of the thorax.
So upon leaving the left ventricle of the heart, the oxygenated blood immediately enters this vessel here highlighted in blue which is known as the aorta. The aorta is the largest blood vessel in the human body and it extends from the heart and travels down through the thorax and the abdomen giving off arterial branches along the way. Here in green, we're looking specifically at the ascending part of the aorta and as you can see, this is a relatively short portion of the aorta which arises just after the aortic root from the left ventricle of the heart. Near the heart, there's a dilated portion of the ascending aorta known as the aortic bulb which we can see better in this image here where the heart has been removed. An important thing to note here about the ascending aorta is that it's the only part of the aorta that does not give rise to arterial branches – and you can see this very clearly in our model on the right.
The next section of the aorta we have here is the aortic arch. And this portion of the aorta, of course, begins after the ascending aorta as we've just seen, and this part of the aorta ascends into an arch going to the left of the mediastinum – as you can see here – and ends at the level of the fourth thoracic vertebral body, T4. There are three arterial branches that arise from the aortic arch and these are the brachiocephalic artery, the left common carotid artery, and the left subclavian artery, and these three branches of the aortic arch supply the head and the upper limbs. We'll look at these three branches in more detail later on. Just a little side note, in some but not all individuals, a constriction in the aortic arch may be present as an embryonic remnant of this part of the aorta, and this particular anatomical quirk is known as the aortic isthmus.
The next section of the aorta is known as the descending part which starts just after the aortic arch and descends down through the thorax and the abdomen and this part of the aorta can be divided into two parts – the first being the thoracic part or the thoracic aorta which descends on the left side of the thoracic vertebrae, T5 to T12, running behind the base of the left lung and the pericardium. The second part of the descending aorta is the abdominal part or the abdominal aorta which begins just after it passes through the aortic hiatus of the diaphragm at the level of the twelfth thoracic vertebral body, T12. It then courses downward along the posterior abdominal wall slightly to the left of the midline and anterior to the vertebral column and terminates at approximately the level of the fourth lumbar vertebral body, L4, where it bifurcates into two other vessels – and you can see this happening on our right.
Along its course through the thorax and the abdomen, the descending aorta gives off important visceral and parietal branches, some of which we'll discuss a little bit later on in this tutorial. So, for the moment, let's move back up to the brachiocephalic trunk and have a bit of a chat about that.
So as we mentioned before, the brachiocephalic trunk is the first branch to arise directly from the aortic arch. It's also known as the innominate artery. The brachiocephalic trunk supplies oxygenated blood to the head and neck as well as the right arm. It also gives rise to two important branches that supply these regions namely the right common carotid artery and the right subclavian artery.
Let's take a look at the two subclavian arteries, and these two main arteries of the thorax get their name from the fact that they lie beneath the clavicles or the collarbones and although the subclavian artery is a paired artery, it has different points of origin on either side. The right subclavian artery, for example, arises from the brachiocephalic trunk as you can see just here while the left subclavian artery arises directly from the aortic arch. It's also the third direct branch that arises from the aortic arch which you can see in this image. Both the left and the right subclavian arteries give off numerous branches before eventually becoming the axillary artery.
Let's talk now about the internal thoracic artery. And the internal thoracic artery is a branch of the subclavian artery and is also a paired artery. Both left and right internal thoracic arteries arise from the anteroinferior aspect of the subclavian artery and pass inferiorly and medially into the thorax giving off both parietal and visceral branches to the chest wall, the mediastinum, the pericardium, the diaphragm and the thymus.
Alright, that's it for the arteries of the thorax. Let's move on now and talk about the arteries that supply the head and neck.
So, there are several important arteries that supply the head and neck and it's easy to get into quite a lot of detail here due to the importance of these vessels and their often unique arrangements but for this tutorial, we're just going to stick to some of the basics, so if you'd like to study these arteries in more detail, of course, be sure to go and check out the website at kenhub.com and have a look around at the other resources that we have for you there. But, for the moment, let's begin with the common carotid artery.
And here in this image on the right, you can see the common carotid arteries and similar to the subclavian arteries, these are paired arteries but with each side having different origins. So the right common carotid artery, for example, arises from the brachiocephalic trunk while the left common carotid artery is the second branch that arises from the aortic arch. So we're just going to bring this image of the head and neck in a lateral view so we can see our common carotid artery a little bit clearer, and as you can see, the common carotid arteries provide the main blood supply to the head and neck regions. And these arteries, of course, course upwards within the carotid sheath along with the internal jugular vein, the vagus nerve and the deep cervical lymph nodes.
Another reason I wanted to show you this viewpoint is because we can see clearly here where the common carotid artery bifurcates at the level of the fourth cervical vertebral body, C4, giving rise to the internal carotid artery here and the external carotid artery which is just here.
Let's now have a bit of a chat about both of these arteries beginning with the external carotid artery. So the internal carotid artery which is one of the two arteries that arises from the bifurcation of the common carotid artery as we just mentioned at approximately the level of C4 gives off several branches which supply the head and neck. And the branches of the external carotid artery are divided into anterior branches, posterior branches and terminal branches. And let's go through some of these. So the anterior branches include the superior thyroid artery, the facial artery, the lingual artery, and the ascending pharyngeal artery while the posterior branches include the occipital artery and the posterior auricular artery, both of which we can see clearly on this lateral view just here. And, of course, finally, the terminal branches include the maxillary artery and the superficial temporal artery.
The other artery that arises from the bifurcation of the common carotid artery is, of course, the internal carotid artery seen here highlighted in green. So as you can see from its origin just here, the internal carotid artery courses superiorly to an area known as the anterior perforating substance where it bifurcates to give rise to the anterior cerebral artery and the middle cerebral artery which form part of a unique network of arteries in the brain known as the Circle of Willis.
I'm just going to take a couple of minutes to explain this a little bit more clearly. So if you can imagine, the internal carotid artery continuing here in green, the anterior cerebral artery comes off like this in blue while the middle cerebral artery is a continuation of the internal carotid artery – and you can see this continuation in blue. And those two as we mentioned form part of the Circle of Willis. The internal carotid artery, of course, gives off a couple other branches but if you want to know more about this, make sure that you go to the website to read some other articles and watch some videos about this artery.
Moving on now, let's look at the major arteries of the upper limb. So as you can see in this image, we're going to start at the thorax and we're going to work our way down the arm, and the first artery that we're going to come into contact with is the axillary artery. And the axillary artery arises as a continuation of the subclavian artery and along its course, the axillary artery also gives off several branches, one of which is known as the brachial artery which arises as a continuation of the axillary artery just here at the inferior border of the teres major muscle and terminates at the elbow joint just here where it bifurcates giving rise to the radial and ulnar branches which we'll talk about in the next couple of slides. It's worth noting that the brachial artery also gives off several other branches before it bifurcates and although we won't be focusing on these in this particular tutorial, it's good to be aware of.
The next artery we're going to be looking at is the deep brachial artery which is a branch of the brachial artery and this artery accompanies the radial nerve along its course and you can see the radial nerve highlighted in yellow. It passes between the medial and long heads of the triceps brachii muscle which it supplies and continues within the spiral groove of the humerus bone after which it divides giving off the middle collateral branch and radial collateral branch – and you can see both of those on our image.
Moving down to look at the major arteries of the forearm now, we can see the radial artery highlighted in green just here, and you may remember from earlier that the radial artery arises as one of the divisions of the brachial artery after it bifurcates at the elbow just here. The radial artery courses down the radial side of the forearm passing distally towards the wrist and terminates in the deep palmar arch of the hand giving off several arterial branches as it travels. It's also worth noting here that the radial artery is also of clinical importance due to its superficial location at the wrists. This is the area where the pulse can be felt to determine the heart rate.
Over on the other side of the forearm, we can see the ulnar artery. The ulnar artery is the second division that arises from the brachial artery after it bifurcates at the elbow – and we talked about this a little bit before in the tutorial. This artery runs distally along the medial or ulnar side of the forearm and goes on to terminate in the hand again giving off several branches at the elbow, forearm and hand along its course.
So now we're finished talking about the arteries of the upper limb, let's move on to talk about the arteries in the abdomen and the pelvis. So let's just have a look at our image of our anatomical woman again just to reorient ourselves, and if we're looking at this image, it really looks like the arteries in this section are really just a mess. The arrangement looks less structured than those that we saw in the upper limbs and later on when we'll look at the arteries of the lower limb, they'll also be perfectly organized in the way that this area is not. But part of the reason why I introduced the descending aorta to you earlier in the tutorial – yes, remember me – is because most of the arteries that we'll be looking at in this section are either direct or indirect branches of the descending aorta. So keeping that in mind will help you stay oriented in this part of the body.
So without further ado, let's move on and talk about the celiac trunk which is this teeny little vessel in green just here and let's zoom in a little bit so we can get a better look. So as you can see, the celiac trunk is an unpaired vessel that arises from the abdominal aorta almost as soon as it passes into the abdomen through the aortic hiatus of the diaphragm. The celiac trunk is also the first anterior visceral branch of the abdominal aorta and although the celiac trunk is a very short vessel – only about one centimeter in length – it serves the massively important function of supplying the foregut via its three major branches which we'll be covering in more detail. And these branches include the left gastric artery, the common hepatic artery, and the splenic artery which we can't see on this particular image but is roughly indicated by this squiggly line.
So let's first talk about the left gastric artery, and the left gastric artery as we mentioned before is the first branch from the celiac trunk and is the smallest of the three branches. And the term gastric refers to the stomach, so if we take a closer look, we can see that the left gastric artery does in fact course along the lesser curvature of the stomach. And the fact that this is called the left gastric artery logically infers that there must also be a right gastric artery, and we can see this here. And as you can see, the two arteries meet here to form what is called an anastomosis which is basically a term for when two otherwise deviating branches of the arteries join together. The left gastric artery supplies the superior portion of the stomach as well as also giving off branches to the esophagus.
Let's talk now about the common hepatic artery which is the next artery to come off from the celiac trunk, and as you can see in the image, it passes to the right towards the lesser sac which is the term for one of the compartments of the abdomen and enters the lesser omentum – another larger abdominal compartment – and it gives off its first branch – the right gastric artery – which as we saw just now supplies the lesser curvature of the stomach on the right side and forms an anastomosis with the left gastric artery. So, the name of this artery is common hepatic artery and as you may know already, the word "hepatic" refers to the liver, however, the common hepatic artery does not supply the liver directly. Instead, it goes on to divide and gives rise to the hepatic artery proper along with the gastroduodenal artery. We can get a better look at these branches in this image just here. So, over here, you can see the right gastric artery, the hepatic artery proper and the gastroduodenal artery, and via these branches, the common hepatic artery supplies several organs including the stomach, the liver, the pancreas and the duodenum.
Let's move on now to talk about the splenic artery indicated here in green. And the splenic artery is the third branch from the celiac trunk and is also its terminal branch. So just taking a look at this image down here, we can see more clearly that it supplies the spleen as its name suggests, and the splenic artery also gives rise to several branches that supply several other abdominal organs including the left gastroomental artery, the great pancreatic artery, the dorsal pancreatic artery and other pancreatic branches as well as the posterior gastric artery.
Moving on now, let's have a look at the gastroduodenal artery which arises from the common hepatic artery. So, the gastroduodenal artery arises posterosuperior to the first part of the duodenum and it gives off branches to the stomach, the pancreas and the duodenum.
Now, let's have a closer look at the right gastroomental artery also known as the gastroepiploic artery, and this supplies the greater curvature of the stomach which you can see just here. The right gastroomental artery joins with the left gastroomental artery which arises from the splenic artery to form an anastomosis.
Now going back to the branches of the abdominal aorta, the next major vessel we will be looking at is the superior mesenteric artery. And this artery arises at approximately the level of the first lumbar vertebra, L1, directly from the abdominal aorta just below the celiac trunk just here, and this artery gives off several arterial branches which go on to supply the various organs of the midgut.
Next, we're going to look at the renal arteries, and these are paired arteries which arise directly from the abdominal aorta at the level of the first and second lumbar vertebral bodies, L1 and L2, to supply the left and the right kidneys as the term "renal" suggests. So note that the right renal artery is longer than the left renal artery due to the position on the abdominal aorta being slightly left of the midline.
Moving down a little bit, we're now going to talk about the gonadal arteries which are, of course, slightly different in males and females so we're going to talk about these separately. First, we're going to look at the lady's. So in this image, we can see the ovarian arteries, and in this image here, we can see the testicular arteries. In both males and females, the gonadal arteries arise directly from the abdominal aorta and they course inferiorly and laterally to the pelvic region to supply the ovaries in females and the testicles in males crossing the ureters anteriorly along their course.
The next artery we're going to be looking at today is located just here and is known as the inferior mesenteric artery which is the third unpaired artery that arises from the anterior aspect of the abdominal aorta just here and this is around about at the level of the third lumbar vertebra, L3. It's also inferior to the gonadal arteries that we just saw which arise from here. The inferior mesenteric artery courses inferiorly to the left side of the midline to supply the abdominal hindgut via several arterial branches including the left colic artery, the sigmoid arteries, and the superior rectal artery.
Let's move on now to the common iliac artery, and at approximately the level of the fourth lumbar vertebral body, L4, just here, the abdominal aorta terminates at which point it bifurcates giving rise to the common iliac arteries and they provide blood supply to the pelvis and the lower limbs. And as you can see, each bifurcates in front of the sacroiliac joint to give rise to the internal iliac artery and the external iliac artery, both of which we'll have a look at next.
So we're going to start first with the internal iliac artery, and the internal iliac artery is the smallest of the two branches of the common iliac artery. This artery supplies the pelvic walls and the viscera, the external genitalia, the perineum and the buttocks as well as the medial part of the thigh. And moving on to the external iliac artery, the external iliac artery is the larger of the two branches of the common iliac artery and it continues on giving off several branches along the way to supply the surrounding structures and enters the thigh region where it continues on as the femoral artery.
Now that we're finished looking at the vessels of the abdomen – the arteries of the abdomen – and the pelvis, let's move on now to talk about the arteries of the lower limb. So we just mentioned the femoral artery in the section just before and as you can see, the femoral artery arises just here as a continuation of the external iliac artery in the femoral region of thigh. It's the main blood supply to the lower limb and it gives off numerous branches before it enters the posterior compartment of the thigh through the adductor hiatus after which it continues as the next artery in this tutorial – the popliteal artery. Now this artery is named after the fact that it passes obliquely through the popliteal fossa at the posterior knee which we can see better in this image just here and passes between the gastrocnemius muscle and the popliteus muscle in the posterior compartment of the lower leg. The popliteal artery gives off genicular branches, muscular branches and sural branches and eventually bifurcates to give off anterior and posterior tibial arteries.
So the anterior tibial artery which we just saw arises from the popliteal artery just here and passes to the anterior compartment of the lower leg at the upper border of the interosseus membrane. It courses downwards between the tibialis anterior muscle and the extensor hallucis longus muscle – both of which you can see just here – giving off several branches along the way, and it eventually terminates distal to the extensor retinaculum after which it continues as the dorsalis pedis artery.
The posterior tibial artery arises from the popliteal artery just here and passes into the flexor compartment, that is, the posterior part of the lower leg. As you can see, it courses behind the medial malleolus or the inner ankle giving off numerous branches along its course and divides into two terminal branches after it passes behind the medial malleolus which are the medial plantar artery and the lateral plantar artery.
The next artery we're going to look at is the peroneal artery which is also known as the fibular artery. The peroneal artery arises from the posterior tibial artery just here and courses laterally to supply the muscles of the lateral compartment of the lower leg and gives off numerous branches along its course.
The final artery we're going to be looking at this tutorial is the dorsalis pedis artery, also sometimes referred to as the dorsal pedal artery. As we saw earlier, it arises from the anterior tibial artery and gives rise to several branches including the deep plantar artery which starts just here and the first metatarsal artery which is just here.
Okay, so now that we've covered all of the major arteries in this tutorial, let's have a look at some important clinical notes relating to the arteries before we go on to quickly recap what we looked at today.
So, the first thing I want to talk to you about regarding the arteries and their clinical pathologies is a condition known as atherosclerosis. So, atherosclerosis is the condition in which plaque builds up within the arteries, and here in this micrograph of an artery, we can see a significant build-up of plaque in the lumen of the artery. Now, the stain that we've used for this micrograph is called Masson's trichrome – and this image shows pretty clearly the narrowing of the lumen of the artery caused by the build-up of plaque which itself can be comprised of cholesterol, fat, calcium or any other components found in blood. As you might be able to guess, this narrowing limits the flow of oxygenated blood which can lead to serious conditions like coronary heart disease, chronic kidney disease, peripheral artery disease and even carotid artery disease as this can affect any of the arteries in the body. And, of course, as you've probably heard, this eventually can lead to heart attack, stroke and even death. Treatment of atherosclerosis can be managed by the use of medications called statins or surgically bypassing the affected artery or by balloon angioplasty with a possible insertion of a stent to open the narrowed artery.
And that's all we're going to talk about with regards to the clinical pathologies of the arteries of the body, and now we're just going to briefly recap all the structures that we looked at during this tutorial.
So going back to the arteries of the thorax, if you remember, we started talking about the ascending aorta which, if you remember, is the only part of the aorta which doesn't have any branches coming off it followed by the aortic arch which gives off three main branches. We then looked at the descending aorta which provides most of the blood supply for the abdomen and the pelvis, and then we went back up and we had a look at the brachiocephalic trunk which gives rise to two important branches – one of which includes the subclavian artery which is a paired artery. This was followed by the internal thoracic artery which is a branch of the subclavian artery and is also a paired artery and then we moved on to the arteries of the head and the neck.
And we began by looking at the common carotid artery which gives off two branches – the external carotid artery and the internal carotid artery – and if you remember, the internal carotid artery gives off a couple of branches which help create the Circle of Willis. We then moved on to talk about the arteries of the upper limb which included the axillary artery which arises as a continuation of the subclavian artery followed by the brachial artery which itself is a branch of the axillary artery. Then we looked at the deep brachial artery which is a branch of the brachial artery and then we looked at the radial artery which is one of two branches of the brachial artery – the other branch being the ulnar artery. And once we're finished with those, we went on to talk about the arteries of the abdomen and the pelvis which included the celiac trunk which is the first of three unpaired branches of the abdomen and the pelvis.
We then looked at the left gastric artery which is the first branch coming off the celiac trunk. Then we looked at the common hepatic artery which does not directly supply the liver. We looked then at the splenic artery which supplies the spleen as its name suggests, then we looked at the gastroduodenal artery which arises from the common hepatic artery. We looked at the gastroomental artery whose left and right arteries create an anastomosis around the greater curvature of the stomach.
We also talked about the superior mesenteric artery which is the second of the unpaired branches in this region and we also talked about the renal arteries which both supply the kidneys. Then we talked about the gonadal arteries which obviously different in men and women. In women, it's the ovarian arteries and in men, it's the testicular arteries. We then talked about the inferior mesenteric artery which is the last of the three unpaired arteries of this region, then we talked about the common iliac artery which bifurcate off the descending aorta as we can see and we talked about the internal iliac artery which is the smaller of the two branches that come off the common iliac artery and we talked about the external iliac artery which is the larger of these two arteries.
Finally, we moved on to the arteries of the lower limb and we began with the femoral artery which is a continuation of the external iliac artery. We then talked about the popliteal artery which passes through the popliteal fossa. The anterior tibial artery as you may recall arises from the popliteal artery and the posterior tibial artery is the other branch that arises from the popliteal artery and supplies the posterior part of the leg. The peroneal artery is also known as the fibular artery and mainly supplies the muscles of the lateral aspect of the leg while the dorsalis pedis artery supplies much of the foot. And then finally, we talked about atherosclerosis which as we mentioned is a condition in which plaque builds up within the arteries which can lead to serious conditions like coronary heart disease and kidney disease and sometimes death.
That's all we have time for today. Don't forget to go to Kenhub and check out our other tutorials. Thanks for watching and see you next time!