Anatomy of the abdominal viscera: Kidneys, ureters and suprarenal glands

Chapters:

Watch video only

Introduction0:00–0:36

Looking to learn about the kidneys and their associated organs. Well, you're in the right place.
The kidneys are a pair of bean shaped abdominal organs which filter metabolic waste out of the blood in the form of urine.
The urine then gets funneled into the urinary bladder by the ureters sitting on top of the kidneys. There are the suprarenal glands or adrenal glands.
These glands function as a part of the endocrine system by secreting adrenal hormones which regulate various functions of the body.
Let's begin with the kidneys which are retroperitoneal organs, meaning they lie posterior to the peritoneum. They lie on the posterior abdominal wall at the level of the T 12 to L3 vertebrae on both the right and the left sides of the vertebral column.

Kidneys0:36–1:03

The right kidney sits slightly lower than the left one which helps make space to accommodate the large size of the liver located on that side of the abdomen.

Anatomical relations1:03–2:05

Now positions superior to both kidneys are the suprarenal glands, but they also have a number of different relationships with surrounding organs.
Anterior to the left kidney is the spleen, stomach, pancreas, left colic flexure and jejunum. While the liver, duodenum, right colic flexure and descending colon lie anterior to the right kidney.
The right kidney and liver are separated by the hepato renal recess, also known as Morrison's pouch. Posteriorly, both kidneys are associated with the diaphragm.
The psoas major quadratus, lubin orum and transversus abdominis muscles as well as the subcostal nerve in vessels and the iliohypogastric and ilioinguinal nerves.
The left kidney is also posteriorly associated with the 11th and 12th ribs. While the right is mainly associated with the 12th rib.
Each kidney has a convex lateral margin and a concave medial margin on their concave margins. Each kidney has a vertical cleft called the renal hilum through which renal vessels, nerves and the ureters enter and exit each kidney at the renal hilum.

Renal hilum2:05–2:46

The renal veins are positioned anteriorly and exit the hilum draining filtered blood away from the kidney. Posterior to the renal veins are the renal arteries which supply blood to the kidney and posterior to the renal arteries is the renal pelvis, which is the superior portion of the ureters which go on to deliver urine to the bladder.
Now, the kidneys are surrounded by several layers of connective tissue and fat which protect and cushion these delicate organs.

External coverings2:46–3:13

When looking at a transverse section of the abdomen. There is the paranephric fat which lies superficial to the renal fascia and then deep to the renal fascia.
There is the paranephric fat. Finally deep in the paranephric fat is the renal capsule, which is a tough fibrous sheath that directly envelops the kidney.

Internal structure3:13–4:19

Now, let's take a look at the internal structure of a kidney in a coronal section on the inside. Each kidney consists of an outer renal cortex and an inner renal medulla.
The functional units of the kidney are called nephrons. And different portions of these microscopic nephrons are found in both the renal cortex and medulla.
No, the renal cortex has extensions that project into the renal medulla, creating segments called renal columns. These columns divide the medulla into pyramidal shaped sections known as renal pyramids.
The base of each renal pyramid is directed towards the cortex and the apex called the renal papilla is directed toward the renal hilum.
The renal papilla is where a urine is excreted into a funnel shaped structure called a minor cally. Many minor calles combine to form two or three major cally which in turn unite to form the renal pelvis, which is the expansion of the superior end of the ureter.

Arterial supply4:19–5:07

The apex of the renal pelvis is continuous with the ureter. Ok.
Now remember that the main job of the kidneys is to filter the waste products out of our blood, which are then eliminated through urine to do.
This blood is delivered to the kidneys by the renal arteries which are direct branches of the abdominal aorta emerging laterally at the level of the L1 to L2 vertebrae just below the root of the superior mesenteric artery.
Now, because the abdominal aorta is located slightly to the left of the spine. The right renal artery is slightly longer than the left crossing posteriorly to the inferior vena cava.
To reach the right kidney at the level of the hilum. Each renal artery typically divides into a number of segmental arteries.

Venous drainage5:07–5:37

Each of which supplies a different renal segment. Venous blood leaves the kidneys via the renal veins which drain straight into the inferior vena cava.
The right renal vein exclusively drains the right kidney. While the left renal vein receives additional tributaries such as the left inferior phrenic vein, left suprarenal vein and the left gonadal vein.
As the left renal vein courses towards the inferior vena cava. It passes anterior to the abdominal aorta and posterior to the superior mesenteric artery.

Quiz5:37–5:56

Now let's hit the pause button. So we can have a quick quiz before we move on from outside to inside.

Ureters5:56–6:45

Remember, the layers of fa and fascia that surround the kidneys. Ok.
Now, after urine is formed in the kidneys, it collects in the renal pelvis and leaves the kidneys through muscular tubes called the ureters which carry the urine from the kidney to the urinary bladder.
The point where the ureters meet the renal pelvis is called the ureteropelvic junction. From there.
The ureters then descend Retroperitoneally in the abdomen anterior to the psoas major muscle. When they reach the level of the sacroiliac joints, they cross the pelvic brim of the pelvic inlet and enter the pelvic cavity while also crossing anteriorly to the bifurcation of the common iliac arteries.

Constrictions6:45–7:13

Then they turn anteromedially at the level of the ischial spines to enter the urinary bladder along the course of each ureter.
There are three constriction points which are common sites where kidney stones can get lodged and obstruct the urinary tract.
The first constriction point is at the level of the ureteropelvic junction. The second constriction point is where the ureters cross the brim of the pelvic inlet and dive sharply into the pelvis.

Arterial supply7:13–7:51

Finally, the last constriction is called the vesicoureteric junction, which is where the ureters enter the wall of the urinary bladder.
The ureters are supplied by a variety of adjacent vessels on their course towards the bladder. The proximal part of each ureter receives its blood supply from the renal arteries.
While the middle part is supplied by branches of the abdominal aorta, gonadal arteries and the common iliac arteries. The distal part of the ureter within the pelvis is supplied by branches from both the superior and inferior vesical arteries, which are branches of the internal iliac arteries.

Venous drainage7:51–8:05

All arteries that reach the ureters divide into ascending and descending branches that form longitudinal anastomoses veins that drain the ureters accompany the arteries.

Quiz8:05–8:19

So the renal veins drain the upper portion of the ureters. The gonadal veins drain the middle portion while the vesical veins drain the lower portion time for a pop.

Suprarenal glands8:19–9:05

Quiz can you name the three constriction points of the ureters where renal stones can get lodged. Now, let's shift gears and talk about these suprarenal glands which are a pair of endocrine glands that sit on the superior pole of each kidney.
The main function of the suprarenal glands is to secrete steroid and catecholamine hormones, steroid hormones like cortisol and aldosterone are involved in stress response in the control of fluid balance and ion homeostasis in the blood.

Anatomical relations9:05–9:44

The suprarenal glands also secrete catecholamines, namely epinephrine and norepinephrine. These hormones are secreted during our sympathetic fight or flight response.
Like if you were to run into a bear at your campsite, helping increase alertness, heart rate, breathing rate and BP. Now, the suprarenal glands are retroperitoneal organs.
The right suprarenal gland is shaped like a pyramid. While the left suprarenal gland is more semilunar in shape.
The suprarenal glands are closely related to a couple of other structures within the abdomen. Both the inferior vena cava and the right lobe of the liver lie anterior to the right suprarenal gland.

Internal structure9:44–10:08

While the right cruce of the diaphragm lies posteriorly, the stomach, the pancreas and the spleen lie anterior to the left suprarenal gland.
While the left cruise of the diaphragm lies posteriorly similarly to the kidneys, the suprarenal glands consist of an outer connective tissue capsule, an outer cortex and an inner medulla.

Arterial supply10:08–10:26

On a cross section. We can identify these three main portions of the suprarenal gland.
The suprarenal cortex produces important hormones, including mineralocorticoids, like aldosterone glucocorticoids such as cortisol, as well as sex hormones like androgens.

Venous drainage10:26–10:44

In contrast, the suprarenal medulla produces catecholamines like epinephrine and norepinephrine. Now, the blood supply to the suprarenal glands is provided by three main arteries.

Lymphatic drainage10:44–11:06

The superior suprarenal artery arising from the inferior phrenic artery, the middle suprarenal artery arising from the abdominal aorta and the inferior suprarenal arteries which arise from the renal arteries.
Venous blood leaves the suprarenal glands through the right suprarenal vein and left suprarenal vein. The right suprarenal vein drains directly into the inferior vena cava.

Innervation11:06–11:42

Whereas the left suprarenal vein drains into the left renal vein and is often joined by the left inferior phrenic vein. All right.
Now, let's talk about the lymphatic drainage and innervation of the kidneys. Ureters and suprarenal glands.
The lymph from both suprarenal glands, kidneys and the upper ureters drains into lateral aortic lymph nodes. While lymph from the lower ureters drains into the common external and internal iliac lymph nodes.

Quiz11:42–11:54

The kidneys are innervated by the renal plexus, which consists of both sympathetic and parasympathetic fibers from the thoracolumbar, splanchnic nerves and the vagus nerve respectively.

Review11:54–13:33

The abdominal portion of the ureters received their innervation from the ureteric plexus, which is supplied by fibers from the renal, the aortic and the hypogastric plexuses.
And finally, the suprarenal glands are innervated by fibers from the celiac plexus. In thoracolumbar, splanchnic nerves, final quiz before we wrap this up can you recall which arteries supply the supra renal glands and where they come from?
All right, as a quick recap, the kidneys are retroperitoneal organs located at the level of the T 12 to L3 vertebrae. They're surrounded by several layers of connective tissue and fat from superficial to deep.
These are the paranephric fat, the renal fascia, the paranephric fat and the fibrous renal capsule, renal vessels, nerves as well as the ureters enter or leave the kidneys through the renal hilum, which is located on the medial side of each kidney.
The ureters are muscular tubes extending from the distal part of the renal pelvis to the urinary bladder. Finally, the suprarenal glands are made up of a tough outer capsule, a cortex and innermost medulla.
The cortex secretes steroid hormones. While the medulla secretes catecholamines.
Anatomy of the abdominal viscera: Kidneys, ureters and suprarenal glands | Osmosis