Spleen and the portal venous system

Question 1

What is the spleen?

Answer 1

Largest lymphoid organ

Question 2

Where is the spleen located?

Answer 2

• In the adult, lies just posterior to the stomach, against the diaphragm and between ribs 8(9)-11 on the left side
• Its long axis is along the 10th rib

Question 3

What are the functions of the spleen?

Answer 3

• Removal of blood-borne antigens
• Removal and destruction of aged or defective blood cells
• Haematopoiesis in the foetus (® 5 months IU)
• Storing blood platelets

Question 4

What is the spleen surrounded by?

Answer 4

• Intraperitoneal except hilum
• Surrounded by a fibrous capsule from which trabeculae extend inward

Question 5

What is the spleen related to?

Answer 5

colon (left colic flexure), stomach and left kidney

Question 6

Describe the superior border of the spleen

Answer 6

notched

Question 7

How is the spleen connected to the stomach?

Answer 7

Connected to the stomach by the gastrosplenic (gastrolienal) ligament

Question 8

What is contained within the gastrosplenic ligament?

Answer 8

• Contains the left gastroepiploic and short gastric vessels
• May contain accessory spleen

Question 9

What is the spleen connected to the abdominal wall by?

Answer 9

Connected to the posterior abdominal wall by the splenorenal (lienorenal) ligament

Question 10

What does the splenorenal ligament contain?

Answer 10

Contains the splenic vessels and the tail of pancreas

Question 11

Answer 11

red = gastrosplenic

green = splenorenal

Question 12

What is the arterial supply of the spleen?

Answer 12

• Splenic artery runs along the upper border of the pancreas
• Divides into its branches that enter the spleen at its hilum

Question 13

What is the venous drainge of the spleen?

Answer 13

• Splenic vein runs along the tail and body of pancreas
• Receives short gastric and left gastroepiploic veins
• Behind the neck of the pancreas, joins the superior mesenteric vein to form the hepatic portal vein

Question 14

What is the lymphatic drainage of the spleen?

Answer 14

Splenic hilar lymph nodes → pancreatic-splenic nodes → coeliac nodes

Question 15

What is the nerve supply of the spleen?

Answer 15

• The nerves accompany the splenic artery
• Sympathetic from T5-9 ⇒ coeliac plexus
• Parasympathetic from vagus

Question 16

What can lead to spleen rupture and what is the consequence of this?

Answer 16

• Because the capsule of the spleen is relatively thin, physical injury (rib fractures, trauma) or a serious infection may cause the spleen to rupture
• Causing considerable intraperitoneal haemorrhage

Question 17

What are the main methods of managing spleen injury

Answer 17

Splenectomy used to be the expected management but nowadays angiography and embolization may be the preferred management along with observation and masterly inactivity

Question 18

Can you live without a spleen?

Answer 18

A person can live a relatively healthy life without a spleen, because macrophages in the bone marrow and liver can take over most of the spleen’s functions. Such a person will be more susceptible to infections

Question 19

What does the hepatic portal system carry?

Answer 19

Carries 70% of the blood to the liver

Question 20

What does the hepatic portal system drain?

Answer 20

Hepatic portal vein drains venous blood between the lower third of the oesophagus and distal half of the anal canal as well as the spleen, pancreas and gall bladder

Question 21

Where is the hepatic portal system formed?

Answer 21

Formed posterior to the neck of the pancreas by the union of the splenic and superior mesenteric arteries

Question 22

Where does the does the hepatic portal vein run?

Answer 22

• Cross the 1st (superior) part of the duodenum and enters the lesser omentum
• Runs cranially in the hepatoduodenal ligament towards the porta hepatis
• Divides into right and left terminal branches
• Neither hepatic portal vein nor its tributaries have valves inside
• The portal vein enters the livers and its branches supply the sinusoids from which blood passes into the central veins → hepatic veins that drain into the inferior vena cava

Question 23

What occurs in the sinusoids?

Answer 23

In the sinusoids the portal venous blood mixes with oxygenated blood from the hepatic artery proper

Question 24

Where are the 4 porto-systemic anastomoses?

Answer 24

• lower third of oesophagus
• halfway down the anal canal
• around the umbilicus
• posterior abdominal wall

Question 25

Answer 25

red = hepatic artery proper

green = central veins

blue = portal vein

Question 26

Desribe the anastomoses at the lower third of oesophagus

Answer 26

• the oesophageal branches of the left gastric vein (portal vein)
• oesophageal veins draining the middle third of the oesophagus (the azygos veins  superior vena cava)
  
  • Oesophageal varices

Question 27

Describe the porto-systemic anastomoses halfway down the anal canal

Answer 27

• The superior rectal vein draining the upper half of the anal canal (portal vein)
• The middle and inferior rectal veins (internal iliac and internal pudendal veins ⇒ inferior vena cava)
  
  • Haemorrhoids (piles)

Question 28

Describe the porto-systemic anastomoses around the umbilicus

Answer 28

• Para-umbilical veins (left branch of the portal vein)
• Epigastric veins (femoral, external iliac, internal thoracic and axillary veins ⇒ inferior and superior vena cava)
  
  • Caput medusae

Question 29

Describe the porto-systemic anastomoses on the posterior abdomimal wall

Answer 29

• Veins of secondarily retroperitoneal organs (including bare area of liver)(portal vein)
• Veins of body wall (systemic veins)

Question 30

What occurs when the hepatic portal vein is diminished or bloacked?

Answer 30

• blood will be shunted to the systemic veins via collateral veins
• Veins will be dilated at sites of porto-systemic anastomoses

Question 31

What are the prehepatic causes of portal hypertension?

Answer 31

• portal vein thrombosis
• splenic vein thrombosis

Question 32

What are the hepatic causes of portal hypertension?

Answer 32

• hepatic tumours (benign, malignant and metastatic)
• cirrhosis (alcohol abuse, hepatitis)
• Parasitic infection (schistomiasis)

Question 33

What are the post hepatic causes of portal hypertension?

Answer 33

• cardiac disease (tricuspid stensosi, restictire cardiomyopathy, contstrive percarditis)
• hepatic vein thrombosis
• inferior vena cava thrombosis

Question 34

Describe the course of the abdominal aorta

Answer 34

• Begins at the aortic hiatus of the diaphragm at T12 (in the midline)
• Lies on vertebral column and descends to the level of L4
• Bifurcates into common iliac arteries (slightly left of the midline)

Question 35

What are the visceral branches of the abdominal aorta?

Answer 35

o Coeliac trunk (L1)

o Middle suprarenal arteries

o Superior mesenteric artery (L1)

o Renal arteries (L1/2disk)

o Testicular or ovarian arteries (L2)

o Inferior mesenteric artery(L3)

Question 36

What are the parietal branches of the abdominal aorta?

Answer 36

o Inferior phrenic arteries

o 4x Lumbar arteries

o Median sacral artery

Question 37

Describe the course of the inferior vena cava

Answer 37

• Retroperitoneal
• Conveys blood from the body below the diaphragm to the right atrium of the heart
• Formed by the union of the common iliac veins behind the right common iliac artery at the level of L5
• Ascends on the right side of the aorta piercing the central tendon of the diaphragm at T8

Question 38

What does the IVC recieve?

Answer 38

o Hepatic veins

o Right inferior phrenic vein

o Right suprarenal vein (left vein drains into the left renal vein or left inferior phrenic vein)

o Both renal veins

o Right gonadal vein (left vein drains into the left renal vein)

o Lumbar veins

Question 39

What are the veins of origin of the IVC?

Answer 39

2 common iliac veins & the median sacral vein

Question 40

Describe the drainage of the lumbar veins

Answer 40

1st-2nd lumbar veins drain both into inferior vena cava and the ascending lumbar veins ⇒ azygos and hemiazygos