In this video I want to talk about the lobes and the structures of the liver.
The liver is found on the upper right side of the abdomen tucked up underneath the costal
margins.
The liver has a very large right lobe and a somewhat smaller left lobe.
And these two lobes are separated by a ligament that spans between the liver and the anterior
inside of the abdominal wall, called the falciform ligament.
The falciform ligament.
As we follow the falciform ligament up on this model we can see that at the top of the
liver it splits and circles around on the liver to connect the liver to the inferior
surface of the diaphragm.
That leaves this portion of the liver actually in contact with our diaphragm.
That area of the liver is known as the bare area of the liver.
And the ligament that outlines that bare area is no longer the falciform ligament, but is
now known as the coronary ligament.
So from this view we can see a large right lobe of the liver and a smaller left lobe
of the liver.
But anatomically the liver has four lobes.
If I turn the liver around and tilt it a little bit, you can see on the superior posterior
portion of the liver we have a small lobe known as the caudate lobe of the liver.
Caudal or cauda means tail.
Anatomists thought this looked like a little tail so they can named it the caudate lobe.
If we look here lower on the liver there is a somewhat four sided lobe right next to the
gallbladder.
This four sided lobe is known as the quadrate lobe of the liver.
The quadrate lobe.
So larger right lobe, a smaller left lobe, a caudate lobe, and a quadrate lobe.
Now if we returned to the anterior view we can see that falciform ligament, and I want
to keep my pointer right at the falciform ligament and then invert this liver.
We see as I round the liver and come to the backside, on the model we see this white line.
This white line is known as the ligamentum teres hepatis.
It is a structure that runs in the lower border of the falciform ligament.
This is the remnants of the umbilical vein in the fetus.
When you were in utero, although mom was doing all of the eating for you, your food came
through the umbilical cord through the umbilical vein and directly into your liver.
Where the liver could process that food and send it to the rest of the body.
So the ligamentum teres hepatis is the remnants of the umbilical vein in the fetus.
And it leads right into an area known as the porta hepatis.
Porta hepatis literally means the doorway to the liver.
At the porta hepatis we can see structures going into the liver and other structures
coming out of the liver.
On this model we can see here the hepatic artery bringing blood into the liver.
At the porta hepatis the hepatic artery will divide into a right and a left hepatic artery.
Here's the right hepatic artery, and the left hepatic artery.
The left the hepatic artery supplies the left lobe of the liver.
The right hepatic artery supplies mainly the right lobe of the liver.
It will also send a branch into the gallbladder.
We will talk about that in just a second.
The other structure we see coming in at the porta hepatis is called the hepatic portal
vein.
Hepatic portal vein is bringing blood from the intestines into the liver where the liver
can do any number of things, we will leave that mostly for lecture.
Liver detoxifies substances in the blood.
Liver converts glucose to glycogen.
So anything that is absorbed in your intestines will go through the hepatic portal vein system
into the liver here at the porta hepatis.
So things coming into the liver, as a fetus you had the umbilical vein, as an adult that
vein his shriveled up and become the ligamentum teres hepatis.
You have the hepatic artery bringing oxygenated blood in.
You have the hepatic portal vein bringing blood that has absorbed nutrients and other
substances in the intestines to the liver.
We also see, at the porta hepatis, structures leaving the liver.
The liver produces bile and bile is used for emulsification of fats.
Bile is stored in the gallbladder.
It is not produced in the gallbladder, it is stored in the gallbladder.
It is produced in the liver, and it will leave the liver by a left and a right hepatic duct.
The right and left the hepatic duct unite to form what we call the common hepatic duct.
The duct from the gallbladder is known as the cystic duct.
When the common hepatic duct and the cystic duct unite we then have a structure known
as the common bile duct.
The common bile duct will then proceed down to the duodenum where it will enter into the
intestines, the small intestines, so that bile can flow from the gallbladder through
the cystic duct, through the common bile duct to the duodenum.
If the sphincter at the duodenum is closed, bile produced in the liver will flow through
the left and right hepatic ducts, the common hepatic duct, into the common bile duct.
But if the sphincter is closed it will back up through the system and through the cystic
duct into the gallbladder.
So again the structures at the area known as the porta hepatis.
We have on this model the common hepatic artery, branching in to the left and right hepatic
arteries, we have the hepatic portal vein bringing blood from the intestines.
And we have coming out, the left and right hepatic ducts uniting to form the common hepatic
duct, uniting with cystic duct to form the common bile duct.
Do not confuse the hepatic portal vein with hepatic veins.
Hepatic portal vein is bringing blood from the intestine into the liver.
This model does not show it, but coming out of the top of the liver going into the inferior
vena cava is where we will find the hepatic veins.
The hepatic veins not seen on this model of the liver.