Description

Liver Function

• Filters blood from the digestive tract via the portal system
• Detoxification of harmful substances
• Produces bile for digestion
• Cholesterol synthesis
• Stores fat and glycogen
• Regulates blood sugar levels

Topography of the Liver (Hepar)

• Holotopy: Right Hypochondriac Region, Epigastric Region, Left Hypochondriac Region
• Skeletopy:
  • Superior Border: Starts at the 10th rib, extends to the 5th intercostal space at the sternum, and ends at the 6th intercostal space
  • Inferior Border: Starts at the 10th rib, extends to the level of the 8-9th rib, and continues to the 6th intercostal space
  • Posteriorly: T9-T11 vertebrae
• Syntopy:
  • Superior Border: Diaphragmatic Surface
  • Inferior Border (Visceral Surface):
    • Pylorus of the stomach
    • Colon
    • Duodenum
    • Right kidney
    • Stomach
    • Esophagus

External Surface of the Liver

Anterior Surface:

• Falciform Ligament (Ligamentum Falciforme)
• Right and Left Lobes
• Inferior Margin (Margo Inferior)

Posterior Surface:

• Posterior Margin (Margo Posterior)
• Bare Area (Area Nuda)
• Right Sagittal Groove (Sulcus Sagittalis Dexter)
  • Groove for Inferior Vena Cava (Sulcus Venae Cavae)
  • Fossa for the Gallbladder (Fossa Vesicae Biliaris)
• Left Sagittal Groove (Sulcus Sagittalis Sinister)
• Round Ligament of the Liver (Ligamentum Teres Hepatis)
• Venous Ligament of the Liver (Ligamentum Venosum)
• Transverse Groove (Porta Hepatis)

Division of the Liver

Lobes of the Liver (Anatomical Division):

• Right Lobe
• Left Lobe
• Caudate Lobe
• Quadrate Lobe

Couinaud Classification (Surgical Classification)

Porta Hepatis

• Common Hepatic Duct
• Hepatic Portal Vein
• Proper Hepatic Artery
• Hepatic Plexus
• Hepatic Lymph Nodes
• Hepatoduodenal Ligament (Ligamentum Hepatoduodenale)

Coverings of the Liver

• Tunica Fibrosa
• Visceral Peritoneum (Tunica Serosa)

Ligaments Around the Liver

Ligaments Connecting to the Diaphragm:

• Falciform Ligament (Ligamentum Falciforme Hepatis)
• Coronary Ligament (Ligamentum Coronarium Hepatis)
• Right Triangular Ligament (Ligamentum Triangulare Dexter)
• Left Triangular Ligament (Ligamentum Triangulare Sinister)

Ligaments Connecting to Other Organs:

• Hepatogastric Ligament (Ligamentum Hepatogastricum)
• Hepatoduodenal Ligament (Ligamentum Hepatoduodenale)
• Hepatorenal Ligament (Ligamentum Hepatorenale)
• Round Ligament of the Liver (Ligamentum Teres Hepatis)

Sources

• Memorix Anatomy 2nd Edition by Hudák Radovan, Kachlík David, Volný Ondřej
• Complete Anatomy by 3D4Medical
• Biorender
• University Notes and Lectures

Transcript

Introduction
0:03
What’s up. Meditay here, and in this video, we’re gonna go through the anatomy of the Liver.
0:08
So now that we’ve gone through all the digestive system structures, along with the three accessory
0:13
organs up here in the mouth, we’ll do the next structure, which is the Liver, since it has an
0:18
essential role in digestion. Our aim in this video is to understand the complete anatomy
0:24
and the orientation of the Liver. And to do that, We’re first going to cover the Function and the
0:28
Topography of the Liver. And then we’re going to look at the external structures of the Liver
0:34
by going through the lobes, margins, and grooves we have on the surface of the Liver,
0:39
and then we’re going to talk about porta Hepatis, along with how the Liver is fixated.
0:43
Basically, going through the covering and the ligaments you’ll find around the Liver.
The Function of the Liver
0:48
So the Liver, or The Hepar in Latin, is the largest internal organ in the body.
0:53
It lies on the right side of the belly and weighs approximately 1.5 kilograms, so it’s pretty heavy.
0:59
The Liver’s main job is to filter the blood coming from the digestive tract before passing it to the
1:05
rest of the body. And it does that through the portal system. And even if you’re not familiar
1:10
with the portal system yet, it is quite important to understand this concept to fully understand the
1:14
anatomy of the Liver. And it’s quite simple, the portal system is just veins that drain
1:20
the nutrients of food from the digestive tract and waste products from the spleen. And when
1:26
all of those veins meet, they become the portal vein, which will go through the Liver. The Liver
1:33
then filters the blood from harmful substances, then sends the blood further into the systemic
1:38
circulation through the inferior vena cava. Now, this is a very simplified scheme of the portal
1:45
system, but I hope you get what I tried to tell you earlier, that it filters the blood coming from
1:50
the digestive tract. The Liver also detoxifies the body by transforming potentially harmful
1:56
substances such as drugs and alcohol into harmless products to be eliminated in The Bile or Urine.
2:03
It also produces cholesterol, which is used for the production of certain hormones, and vitamin D.
2:09
Many nutrients are stored in the Liver as well, including certain fats and glycogen,
2:13
and this glycogen can be used in case of low blood sugar for example.
2:17
So it has many functions. So that is the function, now;
Topography of the Liver
2:19
as always, looking at the anatomy of organs, I always like to start with the
2:23
topography to have the orientation in our heads. So if we add the lines and look at the holotopy,
2:29
meaning the Liver position in relation to the body as a whole. The Liver actually covers
2:34
the whole upper level of the abdominal cavity within the ribs. You will find it in the right
2:39
hypochondriac region, the epigastric region, and extend to the left hypochondriac region.
2:46
From a clinical perspective, we visualize the borders of the Liver by using the skeletopy of
2:51
the Liver. Meaning its position in relation to our bones. As you see right here, the superior border
2:58
starts at the level of the 10th rib and then extends up to the level of the 4th intercostal
3:03
Space at the region of approximately the Right midclavicular line. And then goes to the 5th
3:09
intercostal Space left to the sternum. And then it ends at the 6th intercostal Space,
3:15
so that’s the superior border. Then the inferior border is here, and it also starts at the 10th
3:21
rib at the right side and goes up to the level of the 8th -9th rib, and then continues all
3:27
the way up to the 6th intercostal Space on the left side, where it ends. And then posteriorly,
3:33
you’ll find it between the 9th thoracic vertebra to the 11th thoracic vertebrae
3:37
So that is the Skeletopy of the Liver. Now let’s do the Syntopy of the Liver,
3:42
meaning its position in relation to other organs.
3:45
Let’s look at the superior border first. This is the surface we call the diaphragmatic surface
3:51
because you’ll find the perfectly drawn diaphragm resting on it, as you see here.
3:56
And then the inferior border we call this one the visceral surface, meaning the surface that faces
4:01
different organs. Let’s now zoom. You’ll find the pylorus of the stomach is very close to the
4:07
visceral surface of the Liver. But you’ll also find the upper part of the duodenum,
4:12
you find the Colon, you find the right kidney, and you also find the Oesophagus and stomach,
4:17
the upper part of the stomach lying very close to the superior end of the Liver as well.
External Structures of the Liver
4:22
So that was it for the topography. Let’s now continue with the external structures of the
4:28
Liver. And we’re going to start by looking at the Liver from an anterior view. The first thing that
4:34
catches your eyes is a distinct ligament in the middle called the Falciform Ligament, and this
4:39
ligament separates the right and left lobe. Now the Liver has two margins, right? You
4:45
have the inferior margin projecting downwards. And this margin Is very sharp in shape. And now
4:52
let’s change the angle, and look at the Liver posteriorly. You’ll find this rounded posterior
4:57
margin, which is not as sharp as the inferior one. But an interesting this about the posterior margin
5:04
is that the whole Liver is covered by ligaments and fat, which we call Peritoneum,
5:10
except for this area right here on the posterior margin. We call this the Bare Area,
5:16
or area nuda. It’s bare because it’s the only place that is not covered by fat tissue.
5:22
It’s in direct contact with the diaphragm cuz, remember, the diaphragm lies on top of the Liver.
5:28
So now that we’re looking at the Liver posteriorly let’s go ahead and look at
5:32
its distinct Futures back here. We have three important grooves on the posterior surface.
5:38
The first one is the right sagittal Groove. And the right sagittal Groove is formed by two other
5:44
grooves you’ll find on the visceral surface of the Liver. And here I want you to imagine the inferior
5:49
vena cava running in this direction, forming the Groove for the Inferior Vena Cava, right?
5:55
So the Right sagittal Groove goes like that. It is formed by the fossa for gallbladder, down here.
6:01
and it’s also formed by the fossa for the inferior vena cava, so that’s the right saggital groove it
6:07
separates the right lobe from all the other lobes you’ll find on the posterior view of the Liver
6:13
And then, we have the left sagittal Groove, and to understand this Groove,
6:17
we need to know the ligaments. So down here, we have a ligament called the round ligament
6:22
of the Liver, or ligamentum teres hepatis in Latin. And above that, there’s a ligament
6:27
called the Venous Ligament of the Liver, or ligamentum venosum. And these two ligaments
6:33
form the left sagittal Groove, which separates the left lobe from the rest of the lobes.
6:38
And then finally, we can see one more Groove called The transverse Groove,
6:43
also known as the porta hepatis. Now the porta hepatis is a short depression through which
6:48
all the neurovascular structures and hepatic ducts enter or leave the Liver. We’ll talk more about
6:54
the porta hepatis in a minute, but let’s finish looking at the landmarks on the Liver first.
7:00
So the transverse Groove goes like this and separates the caudate lobe from the quadrate lobe.
Division of the Liver
7:06
Now, we have 4 lobes on the posterior side and 2 lobes on the anterior side, right?
7:12
This is what we call an anatomical Classification or division of the Liver. Dividing it into lobes.
7:18
Don’t confuse this with something called the Couinaud’s system, which divides the Liver
7:23
into eight functionally independent segments where Each segment has its own vascular inflow, outflow,
7:30
and biliary drainage. Knowing this makes it easier to surgically operate segments of the Liver away.
7:36
So keep in mind that we have a classification system based on the landmarks we have on the Liver
7:41
and a classification system that divides the Liver into functionally independent segments.
7:46
So that’s the division of the Liver. Now let’s talk a little bit more about porta hepatis,
Porta Hepatis
7:52
which I’ve highlighted in green right here. As we said earlier, the Porta Hepatis, or the transverse
7:57
Groove, is a short deep depression. And there are a few things that go in and out of this place.
8:03
The most noticeable structure is the common hepatic duct, but you’ll also find the hepatic
8:09
portal vein and the hepatic artery proper going into the Liver through the transverse Groove.
8:16
You’ll also find some hepatic lymph nodes and some nerves called the hepatic plexus
8:21
going through the transverse Groove. And they’re all covered by the hepatoduodenal ligament.
8:27
And this is a ligament that starts off at the Liver and goes down to the duodenum. Therefore
8:32
it’s called The hepatoduodenal ligament. Because it attached the Liver to the duodenum. Now let’s
Coverings of the Liver
8:38
go over and look at the coverings of the Liver. So the Liver is protected, right?
8:43
It’s protected by something called Tunica fibrosa, which is a fibrous sheath, and then on top of it,
8:49
it’s covered by something called the Peritoneum. I’ll talk more about the Peritoneum in another
8:54
video, but for now, Imagine this is a sagittal plane of the abdominal cavity,
8:59
right? Now for orientation sake, this is the Liver, the stomach, the transverse Colon,
9:05
the small intestine, and down here is the sigmoid Colon. Now, this is a woman’s
9:09
abdominal cavity, so the uterus is here. Now, we have something called the Peritoneum,
9:15
and essentially what that Is is a fat layer that is distributed around the abdominal cavity.
9:21
And we divide it into two parts. You have the parietal Peritoneum in Green which covers the
9:27
surrounding walls of the abdominal cavity. And then you have the visceral Peritoneum,
9:32
which covers the organs inside the abdominal cavity here in blue.
9:35
So not only is the Liver covered by Tunica fibrosa, the fibrous layer but it’s also
9:40
covered by the visceral Peritoneum, also called the Tunica serosa. Because the Peritoneum forms
9:46
a serous membrane, which reduces the friction to surrounding structures, that’s why it’s good to
9:51
have this visceral Peritoneum covering the Liver. But the whole Liver is not covered. There is
9:57
actually a place called the bare area. Remember I mentioned this earlier? The bare area,
10:01
which is in direct contact with the diaphragm. So that’s the coverings of the Liver. So to
Ligaments Around the Liver
10:06
understand the anatomy of the Liver fully, you now only need to know the ligament that connects the
10:11
Liver to the diaphragm up there and the ligament that connects the Liver to the other organs.
10:17
SO let’s look at the ligaments around the Liver in a little more detail. So the ligaments from the
10:21
Liver to the diaphragm are three or four because the last one has a Right and a Left ligament.
10:27
Then there’re Four ligaments connecting the Liver to other organs so let’s look at
10:32
the ligaments towards the diaphragm first. The first ligament is this one highlighted
10:36
in green, called the Falciform Ligament, connecting the Liver to the anterior wall.
10:43
And then, if we remove the diaphragm, we’ll see two distinct ligaments on either side
10:48
connected to the falciform ligament in the middle, called the Coronary Ligament.
10:53
This ligament connects to the Liver to the diaphragm. And then again,
10:57
don’t forget that we have the Bare Area, or area nuda here in the middle.
11:01
You’ll see the coronary ligament surrounding it. So if we look at the Liver posteriorly,
11:07
we’ll be able to properly see the coronary ligament surrounding the area nuda. Alright,
11:13
so now we have two more ligaments we can see on this model. And these are the Triangular
11:19
Ligaments. We have the Left triangular ligament, and we have a Right triangular ligament.
11:24
They kind of resemble a triangle, as you see here. Alright, so that was all the ligaments towards
11:29
the diaphragm. Now let’s go over and look at the ligaments that go from the Liver
11:34
towards other organs. These are four ligaments, and they all start from
11:39
porta hepatis. I want you to keep that in mind that all the ligament starts at porta hepatis.
11:44
So the first one is the Hepatogastric Ligament, and as the name says, it goes from the Liver to
11:50
the stomach, or in Latin, it goes from the hepar to the gaster. That’s why it
11:54
gets the name lig. Hepatogastricum. And then the next one is the Hepatoduodenal Ligament,
12:01
going from the Porta hepatis of the Liver to the duodenum. And remember,
12:05
as we saw earlier, This ligament contains the bile duct veins, nerves, arteries, and things
12:11
going in and out from the porta hepatis. So that was the Hepatoduodenal Ligament.
12:17
Next, we have the hepatorenal ligament. Renal means kidney, so this one goes from the Liver
12:23
to the right kidney. And the right kidney is behind here, so it goes like this.
12:28
Some sources might not mention this ligament, as they consider it a part of the coronary
12:33
ligament I mentioned earlier, and some sources might do. Keep that in mind. And then lastly,
12:38
we have the round ligament of the Liver. Or Lig. Teres Hepatis. This one projects anteriorly and
12:45
extends from porta hepatis towards the umbilical ring or the navel. Because It is the remnant of
12:51
the left umbilical vein during fetal life. So that was all I had for the anatomy of the
12:56
Liver. I really hope this video made sense. If it did, please put a like, share, comment.
13:01
Whatever you find convenient to you. See you next time