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 ventral trunk.
And what we’re going to be doing is looking at what you see now on your screen, the anterior view of your trunk and describing all these colorful structures here that are, then, your… the different arteries, different veins, and also nerves that we find in this part of your body, the ventral trunk.
And the first we’re going to start covering are then the arteries that I’m going to list now before we talk about them in a little bit more detail.
So we’re going to be talking about the internal thoracic, the lateral thoracic, the anterior intercostal, superior epigastric, and inferior epigastric arteries. So all of these arteries are going to be discussed on the following slides.
We’re going to start off with the very first one here on the list that you now see here highlighted in green on this image.
And keep in mind that we’re still looking at the anterior view of your chest now or the trunk, but we stripped all of those muscles, and veins, and nerves to just be left with bones and the different arteries that we’re going to be talking about.
Now, these highlighted structures are, if you remember from that list, yes, we’re looking at the internal thoracic arteries.
These structures are going to be supplying the anterior chest wall and the breasts, and they arise from the subclavian arteries, as you can also see here on the image, the subclavian arteries. And notice how the internal thoracic arteries are coming out of these structures.
Now, the internal thoracic artery will be dividing into other branches, including the musculophrenic artery and also the superior epigastric artery around the sixth intercostal space.
We’re moving on to another set of structures or arteries, and here, we just see one on one side. This highlighted artery is known as the lateral thoracic artery.
Now, this one will be arising from the axillary artery, which you can see here on this image. It will be forming different connections, what we call then—a fancy word for it—anastomosis.
And this structure, this lateral thoracic artery is going to be anastomosing with the internal thoracic artery, also the subscapular artery, the intercostal arteries, and with the pectoral branch of the thoracoacromial artery.
Now, as every good artery, this one will be supplying different structures with oxygenated blood, including the serratus anterior muscle, the pectoralis major muscle.
It also sends branches across the axilla to the axillary lymph nodes and also the subscapularis muscle.
Now, in females, it supplies an external mammary branch which turns around the free edge the pectoralis major, then supplies the breasts.
The next structure that we’re going to be talking about, the next artery that you now see here or a set of arteries that you see here, they are known as the anterior intercostal arteries.
Now, they arise from the internal thoracic artery in the upper five or six interspaces and from the musculophrenic artery.
Now, these arteries will also be forming connections with other arteries, which we call anastomosis, with the first interspace with the different branches of the costal cervical trunk and in the other interspaces with the aortic intercostal arteries.
Now, the anterior intercostal arteries will be supplying the external and internal intercostal muscles and also the ribs.
The next one on the list that you see here, this is a paired artery known as the superior epigastric artery. You have two as you can see here on the highlighted image.
Right now, what we did, we just moved a bit further down. We’re still looking at the anterior view of this image, but now, a little bit more focused on the abdominal region.
Now, the superior epigastric artery arises from the internal thoracic artery and will be forming anastomosis with the inferior epigastric artery as you can clearly see here on this image, these are the inferior epigastric arteries.
And you notice how they form some connections here, anastomosis, with the superior epigastric arteries.
Now, the superior epigastric artery will be supplying the anterior part of the abdominal wall and some of the diaphragm.
We’re going to be talking about the next set of arteries, two arteries that we just talked about. If you guess, yes, these are the inferior epigastric arteries.
And these will be arising from these arteries here. I don’t know if you remember from the tutorials where we went over these structures here.
Yes, these are the external iliac arteries, and these are branches… the inferior epigastric arteries are branches of the external iliac arteries.
And as I mentioned on the previous slide, these arteries will be forming connections to, anastomosis with the superior epigastric artery, which you can also see here.
And we form these connections specifically at your navel or also known as a more technical term, the umbilicus.
The inferior epigastric arteries are going to be supplying the anterior and caudal parts of the abdominal wall.
We have now covered the different arteries. We’re moving on to these structures in blue that are known as the veins of the ventral trunk, and I’m going to list them before we go into more detail throughout this tutorial.
We’re going to be seeing the internal thoracic, the anterior intercostal, the thoracoepigastric, the superficial epigastric, the superior epigastric, and then the inferior epigastric.
Let’s start with the very first one here on the list that you see here highlighted in green. These are the internal thoracic vein. Similar to the internal thoracic arteries that we saw.
Arising from the superior epigastric vein, they accompany the internal thoracic artery along its course and drain into the brachiocephalic vein.
The next structures that we’re going to be seeing here now in green, these, as you probably guessed, anterior intercostal veins, like we also saw with the arteries.
The anterior intercostal veins are the veins which drain the anterior intercostal spaces into the internal thoracic vein.
The next structure, next veins that you see here highlighted in green, these are known as the thoracoepigastric veins.
And these are important veins because when your inferior vena cava becomes obstructed, they actually provide a collateral venous return. It creates what is called as a cavocaval anastomosis with the superficial epigastric veins.
Now, the thoracoepigastric vein will be draining into the lateral thoracic vein and also the femoral vein.
The next veins that we’re going to be talking about that you see here highlighted in green, these are known as the superficial epigastric veins.
Now, the superficial epigastric veins are veins which travel with the superficial epigastric vein. It collects blood from the lower and medial parts of the anterior abdominal wall and drains it into the accessory saphenous vein near the fossa ovalis.
There are these structures that we’re going to be talking about, these veins that you see now highlighted in green which are known as, now, the superior epigastric veins.
Now, the superior epigastric veins refer to a blood vessel that carries deoxygenated blood of course, blood from the anterior part of the abdominal wall and some of your diaphragm and then will drain it into the internal thoracic vein.
The superior epigastric vein will be forming an anastomosis or a connection with the inferior epigastric vein, as you can also see here on this image.
And just as we talked about then, it is time to then talk about these structures that you see here highlighted in green. These veins are known as the inferior epigastric veins.
Now, the inferior epigastric veins, they arise from the superior epigastric vein and drain into the external iliac vein, which you can see here on this image. These are the external iliac veins.
We have completed the different veins, the main veins that you find on the ventral trunk. It is time for us to move on and talk about the different nerves that we find in this region of your body.
Now, this will include then the brachial plexus, the medial pectoral nerve, the lateral pectoral nerve, the subcostal, the genitofemoral nerve, and the iliohypogastric nerve, and as well as the ilioinguinal nerve.
We’re going to start off by briefly talking about this structure here, which is known as the brachial plexus, a very important structure that you need to learn in anatomy.
It is quite complex to learn, but we’re going to just briefly mention a few points that you need to know for this particular tutorial.
Now, the motoric and branches of the brachial plexus are irrelevant for this tutorial as they go into or most of them go into your arm.
However, there are other branches directly from the brachial plexus that are worth mentioning, including the subclavian nerve, which runs together with the brachial plexus through the interscalene triangle towards the subclavius muscles, which it innervates.
So, another important branch is the long thoracic nerve, which runs caudally towards the serratus anterior muscle, which is going to then be innervated by the long thoracic nerve.
Additionally, the medial and pectoral nerves arise from the brachial plexus cords, but we’re going to be talking about, right about next, as you can see here on this image, this is the medial pectoral nerve highlighted in green.
And as I mentioned, this one will be arising from this cord here, the medial cord of the brachial plexus.
The medial pectoral nerve will be innervating the pectoral minor and the pectoralis major muscles.
A good way to remember how to differentiate the medial pectoral nerve which pierces both pectorals from the lateral pectoral nerve which pierces only the pectoralis major is this pneumonic here that I use.
The lateral less, medial more. So L-L, M-M. Don’t forget this.
We’re moving on to the next set of nerves that you see here. This is then the lateral pectoral nerves. The lateral pectoral nerves arise from the lateral cord of the brachial plexus.
As you can also here on this image, this is the lateral cord of the brachial plexus and the medial cord here where we also see here the medial pectoral nerve.
The lateral pectoral nerve will be then innervating the deep surface of the pectoralis major muscle.
Although this nerve is described as mostly motor, it also has been considered to transport proprioceptive and nociceptive fibers.
We’re ready to move on to the next ones that you see here highlighted in green. These are known as subcostal nerves. And the subcostal nerves are the anterior division of the twelfth thoracic nerve.
Now, they will be innervating a few structures including the transversus abdominis, the abdominal internal oblique, and also the pyramidalis muscle.
It also gives off a lateral cutaneous branch that supplies the sensory innervation of the skin over the hip.
The next ones that we’re going to also see here, this pair is known as the genitofemoral nerves, and these nerves are found of course on the abdominal region and the genitofemoral nerve originates from the upper L1 to L2 segments of the lumbar plexus.
Will be giving off two branches, the genital branch and of course a femoral branch.
Now, the genital branch passes through the deep inguinal ring and enters the inguinal canal.
In men, the genital branch continues down and supplies the scrotal skin, and in women, the genital branch accompanies the long—the round ligament of the uterus and terminating in the skin of the mons pubis and also the labia majora.
The femoral branch passes underneath the inguinal ligament, traveling adjacent to the external iliac artery and then supplies the skin of the upper and anterior thigh.
We’re going to continue on to the next set of nerves that you see here highlighted in green. These are known as the iliohypogastric nerves. And these are the superior branches of the interior ramus of the spinal nerve, L1.
Will be giving off two branches, and these are the lateral cutaneous branch and the anterior cutaneous branch.
The lateral cutaneous branch will be innervating the abdominal internal oblique muscle and the skin of the gluteal region, while the anterior cutaneous branch will be, then, supplying or innervating the abdominal internal oblique muscle as well, the abdominal external oblique, and the skin of the hypogastric region.
The next pair of nerves that you see here highlighted in green, these are known—and we have now here a few more structures so you can see how these nerves connect to some of the structures that you see here, a few blood vessels as well as some muscles.
These highlighted are then the ilioinguinal nerves.
They are branches of the first lumbar nerve, L1. They separate from the first lumbar nerve along with the larger iliohypogastric nerve, the one we just talked about before.
The ilioinguinal nerve will be, then, innervating the abdominal internal oblique muscle, also the skin of the upper and medial parts of the thigh. And also in males, they will be innervating the skin over the root of the penis and part of the scrotum. And in females, to the skin covering the mons pubis and the labium majus.