Hello all this is Dr.
Kathleen Alsup, and I'm going to provide a quick overview of the liver
The goals of this lecture are to provide you with the big picture ideas associated with the liver to better prepare you for your anatomy
Dissection experience but also importantly in terms of preparing you for the clinical and other basic science lectures that are coming up in the gastrointestinal
sequence
Now as you probably know the liver is considered the largest organ in the
Body, and it takes up a large portion of the abdomen
It is located predominantly in the upper right quadrant of the abdomen
But it also extends into the left upper quadrant
it has a very close association or
Relationship with the diaphragm and you can't see the diaphragm here
But recall in terms of our dissection in the respiratory sequence
You had that diaphragm that you could see and you could feel the liver just deep to the diaphragm
So a very close relationship there. That's why that right dome of the diaphragm is more superiorly placed
Functionally it performs a wide range of metabolic activities required for homeostasis
Nutrition immune defense are particularly important in terms of removal and breakdown of toxic or potentially toxic materials in the blood
There are four gross anatomical lobes of the liver
The right lobe is the largest. It's considerably larger and contributes to all surfaces of the liver
The left lobe is the second largest lobe and if you were just looking
Into the abdomen you would only see the right in the left lobe of the liver
Now in this particular view we're looking at the visceral or the inferior surface of the liver so you can see the other two lobes
associated
You will have both of the quadrate and the caudate lobes
available in this view
The quadrate lobe is located anteroinferior
And is in very close approximation to the gallbladder
So when I'm trying to understand which one is which I try to find that guy
Bladder if it hasn't been removed, and then I know that I'm looking at the quadrate lobe
The caudate lobe is going to be located posterior inferior
These lobes are different than the eight functional divisions
Which are based on the distribution of the portal venous branches in the parenchyma and those particular
Segments are not going to be visible in an intact view of the liver. Just these four gross anatomical lobes
There are considerable
peritoneal
attachments
Associated with the liver and we're going to go over some of the big picture ones and we're going to start with the falciform ligament
You can see the falciform ligament right here in this image
This attaches the liver to the anterior abdominal wall
and when we're talking about within
Dissection that anterior abdominal wall will be reflected in order for us to be able to see all of the abdominal viscera
So it'll already be cut and it will appear as a peritoneal flap between the right and the left lobes of the liver in
the inferior border of that falciform ligament
you'll have your round ligament or ligamentum teres hepatis and this
Continues into a fissure on the inferior surface of the liver
This is the remnant of the umbilical vein that in fetal life opened into the portal vein
The diaphragmatic surface of the liver is covered with visceral peritoneum
Except posteriorly and what we refer to as the bare area of the liver and this is where the livers attach to the diaphragm
by areolar tissue
not by peritoneum
the visceral peritoneum that covers the majority of the rest of the liver are what we refer to as coronary ligaments and
triangular ligaments
one other area that I want to bring to your attention is what's referred to as
ligamentum venosum
and this is the obliterated venous connection between the left portal vein and the left hepatic vein and
Fetally this is referred to as the ductus venosus and you can see the ligamentum venosum
Sitting in the groove for the ligamentum venosum, so very aptly named between the caudate and the left lobe
Lastly in terms of peritoneal attachments are the subdivisions of the lesser omentum
So we're not talking greater omentum, which is by far the more significant portion
We're talking about the lesser omentum and recall the lesser omentum
Is that double layer of peritoneum located between the lesser curvature of the stomach?
To that inferior surface of the liver
The hepato gastric ligament is located between the groove for the ligamentum venosum
so remember
We just saw that on the inferior surface of the liver and it will extend all the way to the lesser curvature of the stomach
The hepato duodenum ligament is another division of the lesser omentum
This is going to be between the porta hepatis
And the duodenum and very importantly it encloses the portal triad and that portal triad
includes the hepatic artery proper, which is a branch of the common hepatic artery the hepatic portal vein and
The the common bile duct. Sometimes you'll see the term common for as well as bile duct
Sometimes you'll just see bile duct and recall that this is a combination of the cystic and the common hepatic ducts
So, let's discuss a little more in terms of the porta hepatis
and this is this deep fissure on the inferior surface of the liver situated between
the
quadrate and the caudate lobe posteriorly
It's going to contain the portal veins
You'll have the left and right branches of the hepatic artery and you will also have your right and left hepatic ducts
Additionally and this doesn't get as much play but it is very important in terms of what will be in located in this area
You'll have the hepatic plexus and nerves and some lymph vessels in
association with a porta hepatis
The main arterial supply for the liver is going to be from the hepatic artery proper
Which is going to give off the right and left hepatic
Arteries and you can see those right in this region here associated with the portal triad
It will branch right before it gets to the liver
There are two Venus systems associated with the liver
You will have the portal and the hepatic or the portal or the systemic. You'll see it three different ways
the hepatic portal vein is formed by your
Superior mesenteric vein and the splenic vein and that will be just posterior to the neck of the pancreas
so a very important relationship there and
It will divide or you'll have two tributaries
Referred to as the right and the left portal veins and that's how that is getting into the liver
The parenchyma is going to be drained by the three main hepatic veins formed by the union of collecting veins
These are going to drain into the systemic system or into the inferior vena cava just inferior to the diaphragm
The parenchyma of the liver is innervated by the hepatic plexus
Which is the largest offshoot of the celiac plexus this contains both sympathetic fibers. It also very importantly carries parasympathetic fibers
one other thing I want to note here is that the capsule that's going to surround the external surface of the liver actually has
innervation from the intercostal nerve so you do have some
Somatic nerves associated with this region as well
This concludes the overview of the liver for additional information and images. Please refer to the blue link website