Hello, everyone. This is Joao from Kenhub, and welcome to another anatomy tutorial where, this time, we’re going to be talking about the neurovasculature of the upper arm.
Now, what we’re going to be doing here on this tutorial is covering the different arteries, veins, and also nerves that supply the shoulder region and also the upper arm. For you to get an idea before we go on and continue on this tutorial, I want to show you the different systems here that we’re going to be covering—so the different arteries, veins, and nerves all put together. And we’re going to be looking at them individually throughout this tutorial and know a bit of how they connect to each other and how they supply this area of your body.
Now, before I do so, what I would like you to do is list the different arteries that we’re going to be talking about. The first one or first set would be the subclavian, the axillary and brachial arteries. We’re also going to talk about the deep brachial artery, the ulnar and radial arteries, the anterior and posterior humeral circumflex arteries, the circumflex scapular, and also the ulnar and radial collateral arteries.
And as we continue throughout this tutorial, we’re going to then move on to the different veins, which include the subclavian, the axillary, and also the brachial vein. We’re also going to talk about the basilic and the cephalic veins.
And later on on this tutorial, we’re going to... or the last part will be, then, the nervous supply of the shoulder and upper arm which basically consists of the nerves, the different nerves that come from the brachial plexus, the different branches that we see there. And this will include then the overview, I would say, of the brachial plexus and the different branches that will, then, go to supply the different structures that you find on the shoulder and upper arm.
Now, we’re going to be seeing that, on the lateral cord of the brachial plexus, there are a set of nerves that are going to be supplying this area, which include the musculocutaneous nerve and the lateral root of the median nerve.
From the medial cord, we’re going to see the ulnar nerve and also the medial root of the median nerve. And from the posterior cord of the brachial plexus, we’re going to be seeing the subscapular nerve, the axillary nerve, and the radial nerve.
And as I mentioned here on this tutorial, we’re going to start with the different arteries of the upper arm. You see now a list of the first three that I want to talk about because there is something important here for us to know that the subclavian, the axillary, and brachial arteries are basically one, big blood vessel. And you can clearly see here on these highlighted images. You notice here the subclavian artery, highlighted in green, followed by the axillary artery which is the continuation of the subclavian, and then you notice here this one, highlighted in green, this is the brachial, which is then the continuation of the previous one that we saw, the axillary artery.
The different names just divide this artery into different sections. And it is important to keep this in mind in order to avoid any sort of confusion as we move on forward.
Let’s start off with the first one here on our list that you can now see, highlighted, from a different perspective. We’re looking at the anterior view of the subclavian artery. Okay. Subclavian “arteries” because you do have two.
Now, it’s important to also add that on the left side of the body, as you can see here, so this is the left side of the subject. And on the left side, this artery, the subclavian, is originating from this structure here known as the aortic arch. While on the right side, the subclavian is originating from this structure here, which is known as the brachiocephalic trunk.
Also important to mention that the subclavian runs through the posterior scalene gap, just between the anterior and medial scalene muscles, and then enters the axilla between the first rib and the clavicle. And from there, it is called then the axillary artery.
Continuing on the subclavian artery, we’re going to now go back to this image. And during its course, this subclavian artery gives off some numerous branches which are worth listing on this tutorial. We won’t go into detail in this tutorial because these branches go towards the neck as well. And we want to focus only on the upper arm for now.
So the first one that I'm going to list now is known as the vertebral artery, which ascends towards the head and is very important for the blood supply of the brain as, then, the basilar artery.
The next one is going to be then the internal thoracic artery that runs caudally next to the sternum supplying mostly the epigastric region. Next branch is going to be then the thyrocervical trunk that gives off branches supplying structures of the neck region.
Finally, we have then the costocervical trunk which then supplies the deep neck region.
We’re now ready to move on to the next artery in our list, now highlighted in green. If you remember well, yes, this is the axillary artery. The axillary artery is the continuation of the previous artery that we talked about, the subclavian artery, which is one of the main supply... blood suppliers of the entire arm.
Now, also an important point to make is how do we separate these two, so the subclavian from the axillary. How do we make the border here? And the way we do so is through the outer edge of the first rib.
Another point I would like to make using this image that you now see under your screen… And keep in mind that we’re still looking at the axillary artery highlighted in green. And another structure here known as—this yellow structure—this is known as the brachial plexus. And what I want to tell you here is that the axillary artery is or lies in close relationship to the brachial plexus, even giving the three cords their names. So you remember... If you remember from the brachial plexus, there is a medial, lateral, and posterior cords. And we name them in a way, thanks to their position in relation to the axillary arteries. So this is an important relationship between this blood vessel and the brachial plexus.
And before we move on to another artery, I would like to then talk about the different branches of the axillary artery. Some of them will be covered here on this tutorial, and the list then includes the subscapular artery, the anterior humeral circumflex, the posterior humeral circumflex, the superior thoracic artery, the thoracoacromial artery, and the lateral thoracic artery. These last three, we’re not going to be covering here on this tutorial as they supply the thoracic regions. So we’ll leave it for another tutorial.
Next structure that we’re going to talk about, now seen highlighted in green, this is known as the circumflex scapular artery. And this comes out of the subscapular artery that is a branch of the axillary artery. And you can clearly see here the axillary artery and then followed by the subscapular artery that will then become the circumflex scapular artery.
Remember this that in Latin, “circumflexus” means “to curve around.” This artery curves around the shoulder and supplies, then, a few structures that are worth highlighting here. These are the scapula as you can clearly see here on this image, this triangular-shaped bone, and also parts of muscles of the shoulder region.
Now, the arteries that you see highlighted in green are known as the anterior humeral circumflex on the left side, and on the right side, we see the posterior humeral circumflex artery. Now, these two arteries run around the humerus and supply, then, the shoulder joint and the head of the humerus with then blood, and as arteries, oxygenated blood.
The next artery that we’re going to be talking about, now seen here highlighted in green, this is another one that you’ve already seen on this tutorial, known as the brachial artery, which is then a continuation of the axillary artery.
Now, in terms of borders, the border of… between the axillary and brachial arteries is then the tendon of the teres major muscle.
Another information that is worth mentioning here on this tutorial about the brachial artery is that it runs down the upper arm, as you can clearly see, and goes until this fossa here known as the cubital fossa. And here, it will split up into its two terminal branches. The brachial artery also gives off several branches that are important for blood supply of the upper arm. These include then the radial artery, the ulnar artery, deep brachial, and superior and inferior ulnar collateral arteries.
Since we already mentioned them, it is worth talking about the radial artery that you see here, highlighted in green, on this image. And the ulnar artery that you see, also highlighted in green, on the right image. And keep in mind that on both of these images, we’re looking at these from the anterior view of the forearm.
You notice here that this is the brachial artery that is forming and splitting up to become the radial and then the ulnar arteries.
And as I mention, both are continuation... Both of these arteries are a continuation of the brachial artery. And they run down the forearm in order to form an anastomosis in the hand known as the deep and superficial palmar arches.
Next in line is this one that you see here, highlighted in green, this artery right about here. This is known as the deep brachial artery. And the deep brachial artery is a big branch of the brachial artery that supplies the muscles of the upper arm with blood.
Now, the arteries that we’re going to be covering are seen here, highlighted in green. On the image on the left side, you see the radial collateral artery. And the image on the right side, you see the superior ulnar collateral artery. Now, both of these images are... we’re looking at the upper arm, and also the shoulder with the scapula here, and the clavicle. But both of these images are… we’re looking at the anterior view of the arm.
Now, the collateral arteries, they grant good blood supply even if one of the bigger arteries is damaged or blocked for some reason.
Now, a few words on the radial collateral artery as you see, now highlighted in green, which comes out of the deep brachial artery making an anastomose with the recurrent radial artery. This is, then, the connection between the deep brachial artery and the radial artery. And you can clearly see here on this image, this is the radial artery, the anastomosis that we’re just talking about and then the radial collateral artery.
The next one is now seen highlighted in green on the image, and we just talked about it. This is the superior ulnar collateral artery. This one comes out of the brachial artery making an anastomosis with the inferior ulnar collateral artery and posterior recurrent ulnar artery. This is then the connection between the brachial artery and the ulnar artery.
And now that we learned the different arteries that will be supplying the shoulder and upper arm, it makes sense to have an idea of how the blood flows from the heart all the way to the tips of your fingers. Now, this is a bit of connecting all the dots here, connecting the different arteries that we just talked about.
So your blood or oxygenated blood is going to be pumped from the left ventricle into the main blood vessel, main artery known as the aorta. And as we’ve seen on the first one of the first slides, then from the aorta, it’s going to go into the subclavian artery, then into the arm through the axillary, and then followed by the brachial artery, which will then split, have the branches known as the radial and ulnar arteries, and then finally it will go all the way to the different branches of the hand.
We are now ready to move on and talk about the different veins of the upper arm and also shoulder. And right now, we are seeing, highlighted, two veins that are known as the equivalent arteries, known as the subclavian veins.
And before I move on, I would like to mention here something that is very important so I would not generate any confusion, that I'm starting at the veins that are closer to the heart moving distally, and I'm going against the blood flow. Because remember that blood flows from the hand back to the heart through… carrying deoxygenated blood but through the veins. But we’re going to talk about the veins on an opposite direction so you can see what happens from the heart all the way to the extremities.
Now, for a bit of location here, to understand what’s going on on this image, you can see here of course the highlighted subclavian veins, and the first ribs, and also the second ribs. We’re looking at these structures anteriorly, and you notice here the thorax cut open.
Now, the subclavian veins, they are close... they run close to then the subclavian arteries. However, it… they do not go through the posterior scalene gap but run anterior to the anterior scalene muscle.
And together with the internal jugular vein, as you can see here—these are the internal jugular veins—the subclavian veins are going to merge with the brachiocephalic vein and then drain blood towards the superior vena cava and then to the heart.
And I want to highlight here an important fact that you need to know, that the thoracic duct, the big, main vessel for the lymphatic system will drain into the subclavian veins.
Let’s start off, then, with this one that you see highlighted in green, which has also a similar name to the artery. This is known as the axillary vein. And just like the arteries, the axillary vein is the continuation of the subclavian vein. It carries blood from the arm, lateral thorax, and axilla. And distally, the axillary vein splits up into two veins known as the brachial vein and also the basilic vein as we move on distally. But note again that veins arise from the dorsal network of the hand towards the heart, while the arteries will then arise from the heart and move or take blood all the way to, then, the periphery.
As we move distally, we’re going to find another blood vessel, another vein here that you see highlighted in green. This is known as the brachial vein. And just like the brachial artery, the brachial vein is the continuation of the axillary vein and distally splits up into the radial and also the ulnar veins.
The next vein that we’re going to talk about is seen now highlighted in green which is known as the basilic vein. This is the other continuation of the axillary vein and runs superficially at the medial side of the lower arm until the dorsal venous network of the hand. It helps draining blood from the hand and lower arm towards the heart.
Next in line, we’re going to have this one that you now see, highlighted in green. This is known as the cephalic vein. The cephalic vein is not a direct continuation but instead a big branch of the axillary vein that runs on the radial side of the lower arm until the dorsal venous network of the hand. This vein is, then, connected with the basilic vein via the median cubital vein at the elbow. And just a fun fact, that we typically use the median cubital vein to draw blood from the cubital fossa.
And before we move on to the nerves, I would like to just take a tour into the main venous blood flow from the hand all the way back to the heart – deoxygenated blood. So I just want to connect all the dots here so you can have a visual understanding of how blood flows from your hand all the way back to your heart through, then, the upper limb.
Now, deoxygenated blood will go from the venous branches of the hand, which will drain the deoxygenated blood into the ulnar radial veins, the basilic vein, and also the cephalic vein. The ulnar and radial veins will drain blood into the brachial vein, and then these three veins: the brachial, the basilic, and cephalic, will drain blood into the axillary vein. And from here, it will go, then, to the subclavian vein, then to the brachiocephalic vein, and now into the superior vena cava, which then will take the blood into the heart.
We’re ready now to move on to the nerves. And you see here, highlighted, what is known to be as the brachial plexus. The brachial plexus is a network of nerve fibers that run from the spine formed by the ventral rami of C5 to C8 and also T1. So it’s formed by the ventral rami of the lower four cervical and first thoracic nerve roots.
Now, the brachial plexus proceeds through the neck, the axilla armpit region, and into the arm, as you can see here on this image.
Now, just a quick overview—very quick because the brachial plexus is a complex topic, and we’re going to be covering it on a separate tutorial—just a quick review that the brachial plexus is divided into roots, trunks, divisions, cords, and also branches. And in this video, we are going to basically talk about some of the cords and some of the branches.
Now, what you see here, the cords are known to be as the lateral cord, as you can see here highlighted in green. There is also now a medial cord that you see now highlighted in green. And this one highlighted as well known as the posterior cord. They’re named, if you remember correctly, by their position in relation to the axillary artery.
Now, numerous branches arise from each cord, however we are going to discuss only the ones, those that are relevant for the upper arm.
Just a quick list here that, on the lateral cord, if you remember from the first list that we looked at, that on the lateral cord we’re going to be talking about the musculocutaneous nerve that is seen highlighted on this image. And also the lateral root of the median nerve comes from the lateral cord of the brachial plexus.
Now, a few words on the musculocutaneous nerve, this nerve innervates the following muscles: the coracobrachialis, the brachialis, and the biceps brachii.
Now, moving on to the median nerve, as you can see now highlighted in green. Now, this nerve has a root that arises from the lateral cord and another one that arises from the medial cord. Both will innervate numerous muscles including the different flexors of the arm and also hand muscles.
Now, the following branches of nerves arise from the medial cord which are the medial root of the median nerve, as you can see here on the left image. And on the right image, you see highlighted, the ulnar nerve. So both of these come from the medial cord.
Now, a quick information here on the medial root of the median nerve, we’ve seen before that the lateral root comes from the lateral cord of the brachial plexus. And you see here the lateral root and the medial root joining to form, then, the median nerve, as you can see here highlighted in green.
We’re ready now to move on to the next nerve of the medial cord of the brachial plexus, seen now highlighted in green. This is known as the ulnar nerve, which runs near the ulna. Now, this nerve is the largest unprotected nerve in the human body meaning that unprotected by, there is no muscle or bone covering it. So it’s quite superficial. It’s quite close to your skin, so injury is commonly associated to the ulnar nerve.
Now, we’re seeing here an image of the elbow, so I can just have here an outline of the ulnar nerve to show you that this nerve is trapped between bone and the overlying skin at the elbow, and bumping it can be painful.
Still on the ulnar nerve, I would like to mention the different muscles that this nerve will be innervating. One will be the flexor carpi ulnaris for example. Another one will be the flexor digitorum profundus and several muscles from the hand.
We’re moving on to another cord of the brachial plexus, this time, seen here highlighted in green. This is the posterior cord. And the posterior cord have branches known as the subscapular nerve, the axillary nerve, and also radial nerve which will be innervating different structures on the upper arm and shoulder.
Starting off with this one here, highlighted in green. This is the subscapular nerve. And this nerve, it supplies the lower part of this muscle that you now see highlighted in green, of the subscapularis. So the subscapular nerve will innervate the lower part of the subscapularis.
And another muscle that will be innervated by the subscapular nerve is the teres major. Another information that you need to know about the subscapular nerve is that it consists of fibers from C5 to C6 of the spinal nerves.
The next one on our list is this one that you see highlighted in green, known as the axillary nerve—also known sometimes as the circumflex nerve. This originates from the brachial plexus at the level of the axilla or armpit and carries nerve fibers from C5 and C6. In terms of upper arm innervation, the axillary nerve supplies, then, the deltoid and teres minor muscles.
The last on the list is this one that you see highlighted in green, and we’re looking at it from the anterior view of the upper arm and also the forearm. This is the radial nerve. And the radial nerve is a nerve in the human body that supplies basically the upper arm, as you can clearly see. Now, it supplies or innervates different structures including the triceps brachii—this muscle is innervated by the radial nerve—also twelve muscles which are mainly responsible for extension of the wrists and digits and supination of the forearm, and also associated joints and overlying skin. So this is an important nerve of the upper extremity as you can see because it is innervating a lot of structures.