Hello, everyone! This is Joao from Kenhub, and welcome to another anatomy tutorial where, this time, we’re going to be covering the neurovasculature of the dorsal trunk and also neck.
So what we’re going to be doing here on this tutorial is looking at your back, as you can see here, and also your neck or the posterior part of your neck and describing the different arteries, also veins and nerves that you find in this region.
And without keeping you waiting, we’re going to start off by listing the different arteries that we’re going to be covering, and these include the occipital, the vertebral, the transverse cervical, the posterior intercostal. We’re also going to talk about the subcostal arteries and lumbar arteries.
And let’s follow this order and start off with this one that you see here or these two that you see here, which are the occipital arteries. And there are two, and they branch out of this artery here, which is the external carotid arteries.
Now, as you can also see, and as you probably remember, the external carotid arteries are going to branch off of these arteries here which are known as the common carotid, which will, then, be splitting into two arteries. One is, then, the external carotid arteries, which you see here, and then these two that you also see here on this image, which are known as the internal carotid arteries.
Now, still on the occipital arteries, I would like to mention some of the structures that these arteries are going to supplying with oxygenated blood, and these include, then, blood to the back of your scalp, also to the sternocleidomastoid muscles, and to the deep muscles in the back and neck.
Now, from this posterior view of the skull and also a bit of the neck here, we’re going to move on to the anterior view to show these arteries that you see here, highlighted in green, which will then go to the posterior portion of the neck, but I wanted to show you first here, from an anterior view, so you can see where they come from. And these are known as the vertebral arteries.
Now, the vertebral arteries are major arteries of the neck, and they branch off of these arteries that you see here, also on this image—that’s why I wanted to show you from an anterior view—the subclavian arteries.
Now, we’re going to move again to the dorsal view that you can still see highlighted in green, the vertebral arteries, to say that the vertebral arteries are going to be supplying blood to the posterior part of the Circle of Willis…
And thus to a significant portion of the brain.
The next arteries that we’re going to be talking about are these that you see now, highlighted in green, and yes, you do have two. These are known as the transverse cervical arteries.
Now, the transverse cervical arteries are arteries in the neck, and they’re branches of the thyrocervical trunk. Now, they split into two branches: a superficial branch and also a deep branch, which you can see here the superficial branch of the transverse cervical artery and also the deep branch.
Now, the superficial branch will be supplying a few structures, including the trapezius and neighboring muscles, as well as lymph nodes in the neck.
Now, the deep branches of the transverse cervical artery are going to be supplying the levator scapulae muscle, the rhomboids, and also the trapezius muscle.
Now that we have this information down, we’re going to move on to a next set of arteries that you see here. Now, these are known as the posterior intercostal arteries.
And if you try to count here on this image, you’re going to notice that there are 11 posterior intercostal arteries on each side of the trunk.
Now, the posterior intercostal arteries are going to be supplying blood to the intercostal spaces, and the first and second posterior intercostal arteries arise from the supreme intercostal artery, which is branch of the costal cervical trunk of the subclavian artery.
Now, the lower nine arteries are known as aortic intercostals, and they have this name because they arise from the back of the thoracic aorta.
We’re moving on to the next set of arteries that you see here. Now, this is a pair which are known as the subcostal arteries.
And the subcostal arteries have their name because they lie below the last ribs, as you can clearly see here on this image. Now, these constitute the lowest pair of branches that derive from the thoracic aorta and are in series with, then, the intercostal arteries.
Now, the subcostal arteries are going to be forming anastomoses with the superior epigastric, lower intercostal, and lumbar arteries.
Now, they give off little branches towards the back, and they supply, then, the anterior and posterior abdominal walls.
Now, we’re going to move on to the next set of highlighted arteries that you see here on the image. These are known as the lumbar arteries. And these are located in the lower back or lumbar region, and they are usually four in number on either side, as you can see here—one, two, three, four.
The lumbar arteries are going to be arising from the back of the aorta. There’s usually a fifth pair, small in size, which is occasionally present, and it arises from the middle sacral artery.
Now, the lumbar arteries are also going to be forming some important anastomoses with other arteries, including the lower intercostal, the subcostal arteries, the iliolumbar, the deep circumflex artery, and the inferior epigastric arteries.
I would like to also add a word on the different structures that the lumbar arteries are going to be supplying, and these include the muscles and skin on the lumbar region, also contents of the spinal canal, and the abdominal wall.
Now that we’re done covering the different arteries, we’re going to move on to, then, the veins, and in terms of veins, we’re going to be talking about the occipital, the deep cervical, the posterior intercostal, the subcostal, and the lumbar veins.
We’re going to, then, follow this list and start off with the very first one that you see here or first ones that you see here, highlighted, which are known as the occipital veins.
Now, the occipital vein begins as a plexus at the posterior aspect of the scalp, and it collects blood from, then, the scalp and the occiput—so basically, from the back of your head, as you can see here on this image.
Now, the occipital veins are going to be draining blood into the venous plexus of the suboccipital triangle by joining the deep cervical and vertebral veins.
The next set of veins that we’re going to be talking about, that you see now, highlighted in green are known as the deep cervical veins.
Now, they’ll be getting in the suboccipital region by communicating branches from the occipital vein, and they collect blood from the deep muscles at the back of the neck.
Now, the deep cervical veins are going to drain blood into the lower part of the vertebral vein.
We’re going to move on to the next one on our list or the next set of veins on our list, which are known as the posterior intercostal veins. And these are veins that drain the intercostal spaces posteriorly, and each vein also gives off a dorsal branch that drains blood from the muscles of the back.
There are 11 posterior intercostal veins on each side, and their patterns are a bit variable, but they are commonly arranged as the following…
And now, I just moved to an image of the open thorax where you can see now the posterior intercostal veins from an anterior view, and you can see a bit better how they connect to other veins.
Now, the first posterior intercostal vein will be draining into the brachiocephalic vein or the vertebral vein… while the second, and third and, often, fourth posterior intercostal veins will be draining into the superior intercostal vein.
Now, the remaining posterior intercostal veins are going to be draining into the azygos vein on the right or to the hemiazygos vein on the left.
We’re now ready to move on to the next set of veins. This is a pair which are known as the subcostal veins, like we saw with the arteries.
Now, these are veins that run along the bottom of the twelfth rib, as you can see here on the image, and they collect blood from the subcostal spaces and drain it into the ascending lumbar vein.
And now that we know this information about the subcostal veins, then it is time for us to move on to the next ones that we saw on that list, a group of veins which are known as the lumbar veins collectively.
Now, the lumbar veins are veins running along the inside of the posterior abdominal wall. And as you have probably guessed by now, they are the lumbar equivalent of the posterior intercostal…
Now, they are the lumbar equivalent of the posterior intercostal veins, and they drain blood from the posterior body wall and lumbar vertebral venous plexuses, and they will be draining into the inferior vena cava.
We’re now ready to move on to the last part of this tutorial. I’m talking about the different nerves that we find in this area of your body.
Now, we’re going to be looking at the greater occipital nerve or nerves, the lesser occipital, we’re also going to be talking about the suboccipital, the supraclavicular, the intercostal, and lastly, we’re going to be talking about the lateral cutaneous branches of the intercostal nerves.
So as you can see, we’re going to be discussing some of the important nerves or main nerves that we find on the dorsal trunk and neck, or posterior neck.
And let’s start off with the very first one on the list, or first ones that you see here highlighted in green, which are known as the greater occipital nerves.
Now, these are spinal nerves, and they innervate the scalp at the top of your head, over the ear, and over the parotid glands.
Now, throughout their course, they’re going to be passing through several neck muscles, including the trapezius.
The next set of nerves that we’re going to be highlighting here are known as the lesser occipital nerves. They are cutaneous spinal nerves arising between the second and third cervical vertebrae.
Now, the lesser occipital nerves are going to be innervating the scalp in the lateral area of the head posterior to the ear.
The next set of nerves that we’re going to be talking about are known as the suboccipital nerves. And the suboccipital nerve is the dorsal primary ramus of the first cervical nerve, C1.
Now, these nerves are going to be innervating the muscles of the suboccipital triangle, the rectus capitis posterior major and minor, and the obliquus capitis superior and inferior.
We’re going to move on to the next ones on our list that you see here highlighted in green. These are known as the supraclavicular nerves.
Now, these arise from the third and fourth cervical nerves, and they can be divided into three: so the medial, intermedial, or lateral or posterior (we can also call it posterior).
Now, I would like to add some information here on these that you see here. These are the lateral posterior supraclavicular nerves that you see on the image right now. And these will be passing over the acromion and the trapezius and will be innervating or be the cutaneous innervation of the upper and posterior parts of your shoulder.
The next set of nerves that we’re going to be highlighting now, on the image, are known as the intercostal nerves.
And the intercostal nerves are part of the somatic nervous system and arise from the anterior roots of the thoracic spinal nerves from T1 to T11, as you can see here on this image—so from T1 all the way down to T11.
Now, the intercostal nerves are going to be innervating a few structures, including the thoracic pleura, the abdominal peritoneum, the intercostal muscles, and also parts of the upper limbs.
Last on our list, we have these that you see here, highlighted in green, which are known as the lateral cutaneous branches of the intercostal nerves. Now, these structures are going to be innervating the skin on the side of the thoracic and abdominal walls. And they divide into the anterior and posterior branches, so we’re looking at the posterior branches right now, that you see highlighted in green on this image.