Video: Ureters in situ
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Hello, everyone! This is Joao from Kenhub, and welcome to another anatomy tutorial where, this time, we're going to be talking about the ureters in situ. And to do so what we’re going to be doing i... Read more
Hello, everyone! This is Joao from Kenhub, and welcome to another anatomy tutorial where, this time, we're going to be talking about the ureters in situ. And to do so what we’re going to be doing is exploring this image that you see now on this screen which is the anterior view of the abdomen where we just removed a lot of the structures here – so a lot of the muscles, the organs and blood vessels – to then expose the structures that we’re going to be covering which are the ureters – as you can see here – and, as the title indicates, we’re going to be exploring the ureters in situ. So, a lot of the structures that you can see around or you can find around the ureters. And notice here that right now, we’re looking at a male model of the abdomen because if you notice here, we see here the rectum and here the urinary bladder.
So, let’s start with the very first structure that you see now highlighted in green on the screen, this one is the abdominal aorta. So, this is the part of the aorta that is found along the posterior wall of the abdomen and it enters here as you can see through the diaphragm, so from the thorax into the abdomen at the level of T12 all the way to its bifurcation here as you can see which happens at the level of L4. Now, if you remember, this abdominal aorta is the continuation of the descending aorta in the abdomen and gives off numerous branches which will supply vital organs in the abdomen and pelvis.
Next, we’re going to go a bit further down to now highlight these two structures that are known as the common iliac arteries. So, here on this image, you can see the right one and here you find then the left common iliac artery. Now, these arteries as you remember from the previous slide, they originate here at this bifurcation of the abdominal aorta which happens at the level of L4. Now, these are two large arteries and they are found on the left and right side of your pelvis. They are about 4 to 5 cm in length and then will give off two very important branches. One is, or two actually are then called the external iliac arteries, and then you can also see here two internal iliac arteries. So, as you can see, both the external and internal iliac arteries are paired arteries.
Speaking of which, we’re going to move on and talk about then and highlight these two structures that you see now on the screen. Now, we’re looking at the external iliac arteries. So, on the left image, we can see then the right external iliac artery while on the right image, you see then the left external iliac artery. And, as I mentioned before, these arteries are then branching off of the common iliac arteries just anterior to the sacroiliac joint. Now, these paired arteries are found on either side of your pelvis and they pass beneath this ligament that you see here on this image, these are known as the inguinal ligaments and, once they cross these ligaments, they will continue on to become the very famous and important arteries known as the femoral arteries – so you have the left one and the right one – so two femoral arteries which are then the main arteries that supply both of your legs. These arteries are important for the blood supply in your lower extremities.
Next, we’re going to be highlighting another branch of the common iliac arteries that I talked about before, these are the internal iliac arteries. Now, the same thing here on the left side you can see then the image showing highlighted the right internal iliac artery while here on this image on the right side, you then see the left internal iliac artery. Now, these are known as the main arteries of the pelvis because their branches will be supplying the walls and also the organs of the pelvis as well as the inner part of the thigh. The internal iliac arteries are smaller than the external iliac arteries but give off several branches which supply the various pelvic muscles and also tissue structures as well as the gluteal muscles and also external genitalia.
The next image we’re going to be highlighting here one artery which is the, to be more specific, the left renal artery but you can also see here on this image the right one. So, now that we have looked at the other arteries that are related to the kidney and ureters, I just wanted this chance to take another look at different structures – different arteries – that are related to the kidneys and ureters.
Now, first, let’s look at the renal arteries which then arise from the abdominal aorta which we talked about before and provide then oxygenated blood to the kidneys. So, there is a left one for the left kidney and then a right renal artery for the right kidney and these will be then supplying oxygenated blood to the left and right kidneys respectively. Now, these blood vessels arise from the abdominal aorta at approximately the level of the intervertebral disc L1 and L2; however, the right renal artery is normally longer than the left renal artery and is located a bit lower than the left renal artery as it must course behind this structure here, the inferior vena cava, and also other structures that you cannot see here on this image like the head of the pancreas and the descending duodenum to get then all the way to the right kidney. Both renal arteries give off several branches – at least 5 or more to be specific – and some of which will be supplying the ureters as well as these structures here which are known as the suprarenal glands before then reaching the hilum of the kidneys.
The next structure we’re going to be seeing here highlighted in green is known as the ovarian artery which are, of course, only found in the female pelvis. Now, the left and right ovarian arteries arise from the abdominal aorta at approximately the level of L2 just below the renal arteries. Now, these 2 paired arteries will be supplying oxygenated blood to the ovaries coursing within then the suspensory ligament of the ovaries. They form an anastomosis also known as the connection with the uterine artery and give off small branches to the ureter and the uterine tube. Now, these arteries enlarge significantly during pregnancy in order to then provide more blood to the ovaries and the uterus.
On the next image, we’re going to be then highlighting this structure which is known as the inferior mesenteric artery. This one arises also from the abdominal aorta at approximately anterior to then L3 to L4 lumbar vertebrae to be specific, and is the third main branch of the abdominal aorta. Now, the inferior mesenteric artery is not paired so this is an unpaired artery and is located to the left side supplying then oxygenated blood to the descending colon, the sigmoid colon, and part of the rectum as well. Now, this artery gives off the left colic artery, several sigmoid branches, and the superior rectal artery. We will be covering a lot of more detail on a separate tutorial. We’re going to be covering this one – this artery – in a little bit more detail.
So, now that we have covered the arteries associated with the kidneys, the ureters and the urinary bladder and also reproductive organs in the female pelvis, let’s move on to then discuss the veins that drain these structures, and we’re starting with these two that you see here highlighted on these two images, now, these are known as the internal iliac veins.
So, the internal iliac veins are paired veins so as you can see here, there is a right one and also a left one. These are sometimes referred to hypogastric veins and the two internal iliac veins join then the external iliac veins which you can also see here on to form then the common iliac veins which you can also see here the same thing as you see with the arteries. So they do so on both the left and right sides of the pelvis. The internal iliac veins, they carry then deoxygenated blood from the veins of the pelvic viscera and the perineum to then the inferior vena cava via the common iliac veins – these veins that you see here – which then connect to this blood vessel here which is the inferior vena cava.
Let’s take a look at another vein, this time this is known as, to be more specific, as the left ovarian vein. The left ovarian vein carries deoxygenated blood from the left ovary and unlike the right ovarian vein which drains directly into the inferior vena cava – and you can also see here, it’s not highlighted – but this one is the right ovarian vein. You see how it drains directly into the inferior vena cava, while the left ovarian vein is then a tributary of the left renal vein which you also see here. It courses through the suspensory ligament of the ovary to then the left renal vein.
The next structure we’re going to be highlighting here is known as – one that we talked about before – this one is the left renal vein. There is also one here, the right one that is not highlighted, but to say that the left and right renal veins drain deoxygenated blood from then your kidneys into this big blood vessel here, the inferior vena cava, which takes then the deoxygenated blood back to your heart. The left renal vein is shorter than the right renal vein as you can see in our illustration due to the position of the inferior vena cava which is located more to the right side of the abdomen. Now, due to this asymmetry, the left renal vein will also be receiving tributaries from the inferior phrenic vein, the suprarenal vein and the ovarian vein which in male – in the male pelvis – is going to be then the testicular vein which does not happen then on the right renal vein.
And since we’re exploring the different structures that exist nearby the ureters, we have to talk about this one. This is the right kidney, to be more specific, but there are two kidneys but just to give a few words on the right kidney. You know that the kidneys, they play a very important role in the urinary system. They are bean-shaped organs – very recognizable – and they are responsible for the removable of excess organic molecules from the blood and also remove by?-products of metabolism and, in addition, the kidneys, they act to regulate electrolytes in the body maintaining then pH balance and blood pressure. Through the production of urine, your kidneys serve to then remove waste products.
The kidneys also facilitate the reabsorption of certain molecules such as glucose, water and amino acids. Among their many functions, the kidneys also produce the hormones known as erythropoietin? and calcitriol and an important enzyme known as renin, which is vital for maintaining blood pressure. Now, the kidneys are located – as you can clearly see here on this image – on the posterior wall of the abdomen in what we call the retroperitoneal space. Also important to note that the right kidney is located slightly lower than the left kidney due to the position of your liver in the abdominal cavity.
And since we talked a little bit about the right kidney, I would like to also add a few words here on this one, the left kidney. Now, this one is located on – as you would expect – on the left side of your body in also the retroperitoneal space sitting slightly higher than the right kidney. For a bit of location, a little bit of mapping here if you want to locate the left kidney, you can say that it’s approximately at the level of T11 to L2 vertebrae. Now, both kidneys together with the adrenal glands that sit on top of them as you can see here, these two structures that I mentioned before. Now, they are surrounded by renal fascia and have two layers of fat between then the kidney and the adrenal glands that sit on top of them.
Now, each kidney has a hilum which is this area right here where the main blood vessels will enter and exit including the ureter as you can see here. They also have a superior and inferior pole, a cortex, a renal sinus which is the initial widening of the ureter, but all these structures we talk about them on a separate tutorial where we explore the actual structure of the kidneys.
I’d like to now move on to the next image where we’re going to start talking about one of the main topics here on this tutorial that you find on the title, the ureters. Now, we’re looking at one part of the ureters which is known as the abdominal part of the ureter. So, these structures – this abdominal part – is the portion of the ureter that goes from the kidney all the way to the pelvis, entering the pelvis. From here on then, it has a different name which we will talk about then later. Now, they are responsible for transportation of urine to then the bladder and the abdominal part of the ureter is then supplied by specific branches of the renal arteries and also branches of the abdominal aorta and gonadal arteries.
And going further down, we’re going to see then this part here that I mentioned before, this one is known as the pelvic part of the ureter. Because as you would expect, this is the actually portion of the ureter that enters or is found within the pelvis. They –as you can see here – they cross the common iliac arteries which you see here on the image. And from here, the ureter then travels downwards before entering the urinary bladder – as you can see here, they are entering the urinary bladder on its posterior aspect – on then the left and right sides. The pelvic part of the ureter which is the closest to the urinary bladder is then supplied by branches of the internal iliac arteries among others.
Now, that we’re looking here at a female model of the abdomen, we can highlight this structure here just for a bit of location to understand that this is the uterus. Just a reminder as well, the uterus is a hollow organ which has about 8 cm in length found in, of course, the female pelvis. And to be more specific, it lies dorsocranially on the bladder and is surrounded by the circumjacent connective tissue that is known as the parametrium. The uterus is divided into a few parts: the cervix, the isthmus, and the corpus. And I suggest you watch a video here on Kenhub where we look at the uterus with a bit more detail and we explained or remind you of how these or where you can find these structures.
Now, this is a reproductive organ of the female pelvis which is then supplied by the uterine artery. The uterine artery is a branch of the internal iliac artery and the uterine branches of the ovarian artery, which is then a branch of the abdominal aorta. As for venous drainage of the uterus, that is then provided by the uterine venous plexus, which drains into then the internal iliac vein. As a reminder here, for innervation of the uterus, now, this organ is innervated by the uterovaginal plexus and the branches of the inferior hypogastric plexus.
Since we talked about the uterus, we should also cover these two structures here which are known as the ovaries. They are essentially the female gonads and they are a bilateral pair of flattened, egg-shaped intraperitoneal discs that reside adjacent to the lateral pelvic wall just inferior to the pelvic inlet. They are surrounded by tunica albuginea which is a fibrous connective tissue. They are also suspended by the mesovarium. Just a few additional words here on the ovaries as reminders that the superior pole of the ovaries is then covered by the fimbriae of the fallopian tubes which are these structures here as you can also see here on this image while the inferior pole is then directly towards the body of the uterus connected to it via the ligament of the ovary.
As for the blood supply of the ovaries, it comes from then the ovarian arteries which are direct branches from the anterolateral surface of the abdominal aorta and they are drained by the left and right ovarian veins. And another organ that you now find here on the female pelvis but you can also find it on the male pelvis, this one is the urinary bladder. This organ, as you remember, serves to then collect urine that is filtered through your kidneys and then arrives via the ureters and is to then be voided through urination.
Now, the urinary bladder is a hollow, muscular and pear-shaped organ that sits on the pelvic floor. The fundus or base of the bladder is formed by the posterior wall and contains what is known to be as the trigone of the bladder which is where the outlet of the urethra is located. The bladder is supplied by the superior vesical artery, the inferior vesical artery, the umbilical artery, and the vaginal artery specifically in the female pelvis. As for venous drainage of this organ is then carried out by the vesical venous plexus and is innervated or the urinary bladder is then innervated by the vesical nervous plexus. So, some information for you to write down just to remind you on your notes but we’re going to cover in a lot more detail on other tutorials where we explore the urinary bladder in a little bit more detail.