Anatomy of the abdominal viscera: Liver, biliary ducts and gallbladder

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Liver0:00–0:30

The liver is quite an amazing organ. And fact is the rumors you heard are true.
It can actually regenerate itself if that wasn't enough. It also plays a major role in digestion by producing bile storing energy, detoxifying toxic substances and producing proteins.
Let's get started and look more at the liver along with the other associated organs and structures that help with digestion.
The liver is a large intraperitoneal organ located mostly in the right hypochondriac and epigastric regions of the abdomen, deep to the seventh to 11th ribs.

Position0:30–0:57

It sits just to the right of the stomach with some of the liver covering its anterior surface. It is superior to the duodenum, right side of the transverse colon and right colic flexure.
Most of the liver is anterior to the lesser omentum and it is anterosuperior to the right kidney and adrenal gland. The liver has many important functions including the production of bile to aid in fat, digestion, reception and metabolization of absorbed products from digestion, detoxification of toxic substances, received from digestion storage and release of carbohydrates as well as the production of proteins, primarily plasma proteins such as albumin and clotting factors.

Function0:57–1:22

Lobes1:22–1:40

When you look closely. The human liver is actually divided grossly into four parts referred to as lobes.
There is a larger right lobe which is separated from a smaller left lobe by the falciform ligament. Then comes the caudate as well as the quadrate lobes which are anatomically included in the right lobe.

Hepatic spaces1:40–2:23

Now, the liver is surrounded by potential spaces which are referred to as hepatic spaces. These spaces usually only contain a small amount of peritoneal fluid which serves as a lubricant between two membranes in close contact.
The hepatic spaces include the right and left subphrenic recesses which are extensions of the peritoneal cavity located on the anterosuperior aspect of the liver and are separated by the falciform ligament.
Next is the subhepatic space which is located between the liver and the transverse colon. This space connects with the hepatorenal recess which extends postero superiorly from the subhepatic space between the liver and the right kidney.
All right. Now, let's look at the two main surfaces of the liver.

Surfaces2:23–3:40

First is the diaphragmatic surface which is in direct contact with the diaphragm and is smooth and dome shaped. Second is the visceral surface which is an irregular surface, molded by neighboring organs such as the gallbladder and the biliary ducts.
The diaphragmatic surface is covered by visceral peritoneum, except on its posterior aspect which is known as the bare area.
The bare area of the liver is in direct contact with the diaphragm. However, it's surrounded by reflections of the visceral peritoneum which form the upper and lower layers of the coronary ligament.
Coronary means crown. So this ligament surrounds the superior surface of the liver like a crown.
These layers of the coronary ligament fuse together on the right to form the right triangular ligament and on the left to form the left triangular ligament, the liver is divided into right and left lobes by the falciform ligament which originates from the ventral mesentery of the embryological foregut in its inferior free margin.
This ligament contains the ligamentum teres hepatis, which translates as the round ligament of the liver. This is the remnant of the fetal umbilical vein which used to carry oxygen rich blood from the placenta to the fetal liver.
All right. Now, let's have a look at the grooves and impressions on the visceral surface of the liver created by the close contact with other organs.

Grooves and impressions3:40–4:59

First, there are two remarkable grooves called the right and left sagittal fissures on the posteroinferior surface of the liver.
These are connected by the porta hepatis, a short transverse fissure where most hepatic vessels enter and leave the liver together.
They look a bit like the letter H. The right sagittal fissure contains a fossa for the gallbladder anteriorly and it continues as the groove for the inferior vena cava along the posterior surface.
The groove for the inferior vena cava also extends into the diaphragmatic surface of the liver. The left sagittal fissure also known as the umbilical fissure contains the fissure for the round ligament anteriorly and continues posteriorly with a fissure for the ligamentum vinosum.
The ligamentum vinosum was actually called the ductus vinosus during fetal life. And its role was to shunt blood from the umbilical vein to the inferior vena cava bypassing the fetal liver.
Now, there is also the hepatogastric ligament, which is actually part of the lesser omentum that extends from the fissure of the ligamentum vinosum to the lesser curvature of the stomach.
The free edge of the lesser omentum located posteroinferiorly to the right is called the hepatoduodenal ligament, which extends between the porta hepatis and the proximal part of the duodenum.

Portal triad4:59–5:21

The hepatoduodenal ligament contains the portal triad, which consists of the bile duct, the hepatic artery proper and the hepatic portal vein.

Arterial supply5:21–6:22

All right, let's now have a look at the blood supply of the liver. It receives blood from two major sources.
The hepatic portal vein and the hepatic artery proper. The hepatic portal vein carries the majority of the blood that enters the liver.
It results from the merging of the splenic and superior mesenteric veins which carry nutrient rich blood from the gastrointestinal tract.
This blood goes straight to the liver, specifically the hepatocytes, which are the liver cells that carry out tasks such as detoxification.
The remainder of the liver's blood supply is oxygen rich arterial blood from the hepatic artery proper, which stems from a branch of the celiac trunk called the common hepatic artery, this artery then bifurcates into the gastroduodenal artery and the hepatic artery proper, which then also bifurcates into the right and left hepatic arteries.
The right and left hepatic arteries mainly supply the non parenchymal part of the liver such as the bile ducts within the liver.
Now, let's talk about venous drainage of the liver within each hepatic lobule. Blood flows from the periphery through sinusoids to a central vein, Blood from the central vein drains into a collecting vein and then into one of three hepatic veins.

Venous drainage6:22–6:51

And finally to the inferior vena cava. The right hepatic vein drains the right lobe of the liver.
The left hepatic vein drains the left lobe and the intermediate hepatic vein which lies between these two lobes drains the central part of the liver.

Lymphatic drainage6:51–7:21

Now let's move on to the liver's lymphatic drainage which is generally divided anteriorly and posteriorly. Most of the lymphatic drainage from the anterior aspect of the liver drains into hepatic nodes around the porta hepatis and from the posterior aspect into front nodes around the bare area of the liver.
Some lymph drainage may also occur along the falciform ligament and round ligament to the parasternal nodes and periumbilical nodes along the anterior abdominal wall.

Innervation7:21–7:35

Finally, the liver's innervation is ensured by fibers from the hepatic plexus. The hepatic plexus receives sympathetic fibers from the celiac plexus and parasympathetic fibers from the anterior and posterior vagal trunks.
All right. Now, before we move on, press pause and recall, the blood vessel that provides most of the liver's blood supply.

Quiz7:35–8:00

Also. Can you try to recall which artery, the common hepatic artery originates from?

Biliary tree8:00–9:00

All right. Now, let's switch gears and have a look at the biliary tree which consists of a series of ducts that carry bile from the liver and gallbladder to the duodenum.
Bile is continuously secreted by hepatocytes from where it drains via canaliculi into interlobular ducts and then collecting ducts which carry it to the left and right hepatic ducts.
These hepatic ducts merge to form the common hepatic duct which is subsequently joined by the cystic duct from the gallbladder to form the common bile duct.
The cystic duct carries bile to and from the gallbladder allowing bile storage and release inferiorly. The common bile duct merges with the main pancreatic duct forming the hepatopancreatic ampulla, also called the ampulla Vater.
The hepatopancreatic ampulla opens into the duodenum at the major duodenal papilla, a muscular valve called the sphincter of adi regulates the flow of bile and pancreatic juice into the duodenum.
Finally, let's have a look at the gallbladder which is a pear shaped intraperitoneal sac lying in a fossa on the visceral surface of the right lobe of the liver, lateral to the quadrate lobe and just anterosuperior to the duodenum.

Gallbladder9:00–9:28

The gallbladder's main function is to concentrate and store bile produced by the liver as well as release it after a meal that contains fats to help with their digestion.
The gallbladder has three parts, a rounded distal part called the fundus. The body which is the largest part laying adjacent to the visceral surface of the liver, the transverse colon and the upper part of the duodenum.

Structure9:28–10:02

And finally, the neck of the gallbladder, which is the tapering end where the cystic duct extends from the mucosa of the neck of the gallbladder.
And the cystic duct creates a spiral fold, also called the spiral valve, which helps to keep the cystic duct open to allow for the easy flow of bile for storage or release.
The gallbladder's blood supply comes from the cystic artery, which is a branch of the right hepatic artery arising in the cystohepatic triangle of ko This triangle is a space bounded by the common hepatic duct.

Arterial supply10:02–10:21

The cystic duct and the visceral surface of the liver venous drainage from the neck of the gallbladder. And the cystic duct is provided by cystic veins which may enter the liver directly or empty into the hepatic portal vein.

Venous drainage10:21–10:40

The veins draining the fundus and body of the gallbladder directly enter the visceral surface of the liver and empty into hepatic sinusoids.
Lymph from the gallbladder drains to the cystic lymph nodes located at the gallbladder's neck. In turn, these nodes empty into the hepatic and the celiac lymph nodes.

Lymphatic drainage10:40–10:54

The gallbladders sympathetic and sensory innervation is provided by the celiac plexus. While the vagal trunks contribute to this plexus providing parasympathetic innervation.

Innervation10:54–11:07

Quiz11:07–11:23

Before we recap which two ducts come together to form the common bile duct. All right, as a quick recap.

Review11:23–12:54

The liver is an intraperitoneal organ located beneath the diaphragm within the right hypochondriac and epigastric regions.
It has a left and right lobe separated by the falciform ligament as well as a caudate and quadrate lobe, which are considered part of the right lobe.
The majority of the liver's blood supply comes from the hepatic portal vein. While the remaining comes from the hepatic artery proper, its venous drainage is provided by the left right and intermediate hepatic veins.
Well, its nerve supply comes from the hepatic plexus, which includes fibers from anterior and posterior vagal trunks. The bile produced by the liver is drained through the left and right hepatic ducts which join to form the common hepatic duct.
Then the common hepatic duct is joined by the cystic duct from the gallbladder forming the common bile duct. The common bile duct merges with the main pancreatic duct forming the hepatopancreatic ampulla which opens into the duodenum at the major duodenal papilla.
Finally, the gallbladders located on the inferior surface of the liver and consists of three parts, the fundus, the body and the neck.
The gallbladder is supplied by the cystic artery, drained by the cystic veins and receives its innervation from the celiac plexus, which includes contributions from the vagal trunks