Description

This video provides a detailed breakdown of the Portal Venous System, including its tributaries, anatomical significance, and the clinical relevance of porto-caval anastomoses.

1. Portal Venous System

The portal venous system drains blood from the unpaired visceral organs, including the:

• Large Intestine
• Small Intestine
• Pancreas
• Stomach
• Spleen
• Gall Bladder

2. Formation of the Portal Vein (Vena Portae Hepatis)

The portal vein is formed by the union of the following major veins:

• Superior Mesenteric Vein (Vena Mesenterica Superior)
• Splenic Vein (Vena Splenica)
• Inferior Mesenteric Vein (Vena Mesenterica Inferior)

3. Tributaries of the Portal Vein

Superior Mesenteric Vein

• Jejunal and Ileal Veins (Venae Jejunales et Ileales)
• Right Colic Vein (Vena Colica Dextra)
• Ileocolic Vein (Vena Ileocolica)
• Appendicular Vein (Vena Appendicularis)
• Middle Colic Vein (Vena Colica Media)
• Right Gastro-omental Vein (Vena Gastroomentalis Dextra)

Inferior Mesenteric Vein

• Opens into either the splenic vein, superior mesenteric vein, or the portal vein.
• Superior Rectal Vein (Vena Rectalis Superior)
• Sigmoid Vein (Vena Sigmoideae)
• Left Colic Vein (Vena Colica Sinistra)

Splenic Vein

• Starts from the splenic hilum.
• Left Gastro-omental Vein (Vena Gastroomentalis Sinistra)
• Short Gastric Veins (Venae Gastricae Breves)
• Pancreatic Veins (Venae Pancreaticae)

Portal Vein Direct Tributaries

• Left Gastric Vein (Vena Gastrica Sinistra)
• Oesophageal Veins (Venae Oesophageae)
• Right Gastric Vein (Vena Gastrica Dextra)
• Prepyloric Vein (Vena Prepylorica)
• Pancreaticoduodenal Veins (Venae Pancreaticoduodenales)
• Cystic Vein (Vena Cystica)
• Paraumbilical Veins (Venae Paraumbilicales)

4. Porto-Caval Anastomoses

Porto-caval anastomoses connect the portal system to the systemic (caval) venous system. These play a crucial role in cases of portal hypertension, where blood is redirected due to increased pressure in the portal system.

Causes of Portal Hypertension

• Hepatic Causes: Liver cirrhosis (from alcoholic liver damage, non-alcoholic fatty liver disease, Hepatitis C infection, metabolic disorders).
• Pre-hepatic Causes: Portal vein thrombosis, tumors.
• Post-hepatic Causes: Right-sided heart failure.

Major Porto-Caval Anastomoses

1. Esophageal Anastomoses

• Oesophageal veins drain into the azygos and hemiazygos veins, which empty into the superior vena cava.
• Clinical Relevance: Increased pressure in the portal system can lead to esophageal varices—a life-threatening condition.

2. Rectal Anastomoses

• Superior Rectal Vein (portal system) anastomoses with:
  • Middle Rectal Vein → Internal Iliac Vein (caval system).
  • Inferior Rectal Vein → Internal Pudendal Vein (caval system).
• Clinical Relevance: Increased portal pressure may lead to internal hemorrhoids.

3. Paraumbilical Anastomoses

• Paraumbilical veins (portal) anastomose with superficial epigastric veins and thoraco-epigastric veins (caval).
• Clinical Relevance: Causes Caput Medusae (appearance of engorged veins around the umbilicus).

4. Retroperitoneal Anastomoses

• Veins from the colon (portal) anastomose with lumbar veins (caval).

5. Clinical Relevance: Ascites

Severe portal hypertension may also lead to ascites, the accumulation of fluid in the peritoneal cavity.

Sources Used:

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

Transcript

Introduction
0:00
[Music]
0:03
what’s up melte here
0:05
now now that we’re done with the
0:06
inferior vena cava and the superior vena
0:09
cava let’s finally cover the portal
0:11
venous system
0:13
now the portal venous system is a system
0:15
of veins that drain blood from the
0:17
unpaired organs of the abdominal cavity
0:20
these are the large and the small
0:22
intestine the pancreas and the stomach
0:25
the gallbladder and the spleen
0:27
so blood from these organs will
0:29
eventually find its way into the portal
0:31
vein which go within the hepatoduodenal
0:34
ligaments into the liver it then
0:36
bifurcates into the right and the left
0:38
branches then divides into smaller
0:40
branches to supply the hepatic lobes
0:43
that’s why we say all the medications
0:45
that you take all the food that you eat
0:47
once they’re absorbed from the
0:48
intestines they will all go through the
0:51
liver within this system to be processed
0:53
and filtered before going into the
0:54
systemic circulation
0:56
and keep in mind this goes for the
0:58
exocrine hormones from the pancreas as
1:00
well like the insulin so the portal
1:03
system is an extremely important system
1:06
it makes sure to include the liver to
1:08
take part in processing stuff so let’s
1:11
go ahead and see how these veins are
1:12
arranged so the portal vein is formed by
1:15
three major veins and these are the
1:18
superior mesenteric vein the splenic
1:21
vein and the inferior mesenteric vein so
1:24
let’s go ahead and go through all the
Superior Mesenteric Vein Tributaries
1:26
tributaries of the portal venous system
1:28
starting with the superior mesenteric
1:30
first the superior mesenteric vein
1:33
passes on the right side of the superior
1:36
mesenteric artery and it goes behind the
1:38
pancreas it goes down and then
1:41
terminates as the jejunal and the ileal
1:43
veins they both collect blood from the
1:45
loops of the jejunum and the ilium
1:47
then it has the right colic vein for the
1:50
ascending colon the ileucolic vein which
1:54
collects blood from the terminal part of
1:56
the small intestine and the cecum hence
1:58
the name ileocolic vein it also has a
2:00
small tributary vein called the
2:02
appendicular vein which receives blood
2:04
from the appendix
2:06
other veins that drain into the superior
2:08
mesenteric are the middle colic vein
2:11
which collects blood from the transverse
2:13
colon and the right gastro-or mental
2:16
vein which collects blood from the
2:18
greater curvature of the stomach and the
2:20
greater momentum of the peritoneum as
2:22
well
2:24
so the superior mesenteric receives
2:27
blood from all of these veins and dumped
2:29
them into the portal vein
Inferior Mesenteric Vein Tributaries
2:31
awesome one down let’s do the inferior
2:34
mesenteric vein
2:35
the inferior mesenteric vein as we said
2:38
usually opens into the splenic vein
2:41
behind the pancreatic head
2:43
but keep in mind that veins are very
2:45
variable there are some cases where it
2:47
can open into the superior mesenteric
2:49
vein as well or directly into the portal
2:51
vein but in the majority of cases it’s
2:54
going to open into the splenic vein and
2:56
keep in mind that when we say the portal
2:59
vein is formed by the mesenteric veins
3:01
and the splenic vein in reality it’s
3:04
formed by a lot of different tributaries
3:06
but the mesenteric veins and the splenic
3:09
vein these are very large veins within
3:11
the system and since the majority of
3:13
blood that the portal vein receives come
3:15
from these three veins we say that it’s
3:18
usually formed by these three veins
3:19
right here so
3:21
that’s why the inferior mesenteric vein
3:23
even though it doesn’t directly open
3:25
into the portal vein in the majority of
3:27
cases it still receives a huge majority
3:30
of blood from the inferior mesenteric
3:32
vein that’s why in some sources you will
3:34
find that the inferior mesenteric vein
3:36
takes part in forming the portal vein as
3:39
well alright so the first tributary is
3:42
the superior rectal vein receiving blood
3:44
from the superior part of the rectum or
3:47
the rectal ampulla
3:48
then we have the sigmoid vein which
3:50
collects blood from the sigmoid colon
3:53
and the left colic vein for the
3:55
descending colon so again the inferior
3:58
mesenteric vein collects blood from all
4:01
of these veins and dumped them primarily
4:03
into the splenic vein
Splenic Vein Tributaries
4:06
so let’s now cover the splenic vein the
4:09
splenic vein originates from the splenic
4:11
helium as you see here
4:13
then it passes behind the stomach and
4:15
the pancreatic body to join the superior
4:18
mesenteric vein in forming the portal
4:21
vein
4:22
so first off it has a vein that
4:23
communicates with the right gastrointel
4:25
vein called the left gastroemonical vein
4:28
it has a short gastric vein which goes
4:31
up and drains the fundus and the upper
4:34
greater curvature of the stomach
4:36
then it has the pancreatic veins which
4:39
arise along the surface of the
4:40
pancreatic body and drain it into the
4:43
splenic vein and so just to visualize it
4:46
a little better
4:47
here we see the portal vein the superior
4:50
mesenteric the splenic vein the inferior
4:53
mesenteric and here are the pancreatic
4:56
veins and as you see here the splenic
4:58
vein goes behind the pancreas and the
5:01
pancreatic veins originate from the body
5:04
and the tail of the pancreas to empty
5:06
into the splenic vein
5:08
after that the splenic vein empties into
5:11
the portal vein so that was the splenic
5:14
vein as well
Portal Vein Tributaries
5:16
now let’s go ahead and cover the
5:17
tributaries of the portal vein
5:20
first we have the left gastric vein
5:22
which collects blood from the lesser
5:23
curvature as you see here and it also
5:26
receives blood from the abdominal part
5:28
of the esophagus as the esophageal veins
5:31
then the left gastric vein will
5:33
anastomose with the right gastric vein
5:35
to form a venous arch along the lesser
5:38
curvature so the right gastric vein will
5:41
collect blood from the lesser curvature
5:43
and it will also receive blood from the
5:45
pre-polaric vein draining the pyloric
5:48
part of the stomach
5:49
so that’s these two
5:51
then we got the pancreatic duodenal vein
5:54
which collects blood from the head of
5:56
the pancreas and the duodenum as well
5:59
and then it empties into the portal vein
6:02
it can also empty into the superior
6:04
mesenteric vein sometimes it depends on
6:06
the source you’re starting from
6:08
then there’s the cystic vein collecting
6:10
blood from the gallbladder and then we
6:12
got the para umbilical veins which are
6:15
two thin veins passing along the round
6:18
ligament of the liver to drain blood
6:20
from the anterior part of the abdominal
6:22
wall and some parts of the diaphragm as
6:24
well directly into the liver and keep in
6:27
mind that it does communicate with other
6:29
veins of the anterior abdominal wall as
6:31
well
6:32
so that was all the veins of the portal
6:35
venous system
6:36
all of these veins unite to form the
6:39
portal vein and the portal vein goes
6:42
into the liver and branches off to
6:44
various lobes and then the right
6:48
intermediate and the left hepatic veins
6:50
drain blood from the liver into the
6:52
inferior vena cava so that is how the
6:56
blood goes from the portal system into
6:58
the systemic circulation all right
Porto-Caval Anastomoses
7:00
now there’s a concept that you need to
7:03
be familiar with because it’s very very
7:05
clinically important and that concept is
7:08
called the portal cable anastomosis this
7:11
is an anastomosis or a connection
7:14
between the tributaries of the portal
7:16
vein and the superior or the inferior
7:18
vena cava hence the name portal cable
7:21
anastomosis
7:23
now
7:24
here i’ve combined all the portal veins
7:27
under physiological condition blood
7:30
flows from the portal vein to the liver
7:33
right
7:34
under any circumstances that make the
7:36
blood pressure in the portal system
7:38
increase there’s going to be a problem
7:40
right this condition is called portal
7:43
hypertension
7:44
so just to throw in a couple of examples
7:46
if there’s chronic damage to the liver
7:49
due to excessive alcohol consumption or
7:51
non-alcoholic fatty liver disease or
7:54
hepatitis c infection or you know other
7:57
metabolic causes the body is going to
8:00
replace the damaged cells with fibrotic
8:02
tissue right called liver cirrhosis it
8:06
could also be pre-hepatic causes like
8:08
portal vein thrombosis or any external
8:11
compression of the portal vein by masses
8:13
like a tumor or post hepatic causes like
8:16
right-sided heart failure because
8:18
remember if the right side of the heart
8:20
is failing the blood will start to build
8:22
up in the superior and the inferior vena
8:25
cava which in terms also congests the
8:28
blood inside the portal system
8:30
so whatever the cause will lead to
8:32
portal hypertension
8:34
now the blood needs to escape the portal
8:37
system right
8:38
and since it’s not flowing through the
8:40
liver as efficiently as you want it to
8:43
it has to escape through other places
8:45
through the portal cable anastomosis
8:48
so blood flows through these veins
8:50
normally but if there’s an increase in
8:53
portal pressure the anastomotic veins
8:55
will also start to congest leading to
8:58
varices or ascites so let’s go ahead and
9:01
go through the portal cable anastomosis
9:03
a little bit
9:04
through the esophageal veins blood will
9:07
go up to the esophagus and anesthetize
9:09
with the esophageal veins of the asicus
9:12
and the hemiasicus veins and then it
9:14
will flow into the superior vena cava
9:18
so in other words there’s an anastomosis
9:20
between the esophageal veins
9:23
now suppose there’s an increased
9:25
pressure in the portal system
9:27
in that case these veins will start to
9:29
get congested with blood leading to
9:31
esophageal viruses which can be seen
9:34
during an upper endoscopy
9:36
then there’s an anastomosis in the
9:38
rectum
9:39
and this anastomosis happened through
9:42
the superior rectal vein that drain into
9:44
the inferior mesenteric vein the middle
9:47
rectal vein that drains into the
9:49
internal iliac vein and the inferior
9:52
rectal vein which drains into the
9:54
internal pudendal vein
9:56
if there’s an increase in portal
9:58
pressure blood will get congested in the
10:01
hemorrhoidal plexus forming internal
10:03
hemorrhoids
10:04
now just keep in mind that increased
10:07
partial pressure is an infrequent cause
10:09
of hemorrhoids so if you see a patient
10:11
with hemorrhoids the chances of it being
10:14
because of increased portal pressure are
10:16
low
10:16
but you know theoretically it’s possible
10:19
all right
10:20
then there’s an anesthemosis between the
10:23
para umbilical and the subcutaneous
10:26
veins around the umbilicus
10:28
when these veins enlarge they get the
10:30
term kaput medusa or head of the medusa
10:33
the name originates from the apparent
10:35
similarity of medusa’s head which had
10:38
venomous snakes as hair
10:40
so they ended up calling this condition
10:42
after because they look alike
10:44
and these anastomoses happen between the
10:47
thoracoepigastric veins which open into
10:50
the axillary vein and the superficial
10:53
epigastric veins and this condition is
10:55
also very characteristic for portal
10:57
hypertension
10:58
other signs are
11:00
you know when you have congested blood
11:02
water starts to go out from the veins
11:05
filling up the peritoneal space leading
11:08
to ascites
11:09
so
11:10
that was all i had for the portal venous
11:12
system and its anastomosis
11:14
i really hope you found this video
11:15
helpful if you did please put a like
11:18
comment and subscribe see you next time