Spleen and Portal Venous System

Question 1

What are the functions of the spleen?

Answer 1

• removes blood borne antigens
• removes and destroys aged or defective blood cells
• stores blood platelets and RBCs
• haematopoiesis in foetus (before being taken over by bone marrow later in development)

Question 2

What is the location of the spleen?

Answer 2

• lies just posterior to stomach against diaphragm and between ribs 9-11 on left side
• long axis along 10th rib posterior to mid-axillary line
• intra-peritoneal organ except hilum

Question 3

What are the relations of the spleen?

Answer 3

• colon (left colic flexure)
• stomach
• left kidney

Question 4

What are the connections of the spleen?

Answer 4

• connected to stomach by gastrosplenic ligament (contains left gastroepiploic and short gastric vessels)
• connected to posterior abdo wall by splenorenal ligament (contains splenic vessels and tail of pancreas)

Question 5

What is the arterial supply and venous drainage of the spleen and their derivations?

Answer 5

• splenic artery (running along upper border of pancreas - divides into branches to enter spleen at hilum)
• splenic vein (running along the tail and body of pancreas - receives short gastric and left epiploic veins, joins superior mesenteric vein to form hepatic portal vein)

Question 6

What is the lymphatic drainage and nerve supply of the spleen?

Answer 6

• splenic hilar lymph nodes to pancreatico-splenic nodes to coeliac nodes
• supplied by nerves that accompany the splenic artery
• sympathetics from T5-9 (coeliac plexus)
• parasympathetics from vagus

Question 7

Describe the clinical implications of the anatomy of the spleen

Answer 7

the spleen is surrounded by a thin capsule which can be punctured in physical injury and cause the spleen to rupture which causes intraperitoneal haemorrhage

Question 8

Describe the anatomical position of the abdominal aorta

Answer 8

• begins at aortic hiatus at T12
• lies on vertebral column and descends to L4 before bifurcating into common iliac arteries
• retroperitoneal

Question 9

What are the visceral branches of the abdominal aorta?

Answer 9

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• coeliac trunk (T12/L1)
• middle suprarenal arteries
• superior mesenteric artery (L1)
• renal arteries (L1/2 disk)
• testicular or ovarian arteries (L2)
• inferior mesenteric artery (L3)

Question 10

What are the parietal branches of the abdominal aorta?

Answer 10

• inferior phrenic arteries
• 4x lumbar arteries
• median sacral artery

Question 11

Describe the anatomical position of the IVC

Answer 11

• retroperitoneal

- formed at T5 and ascends on right side of aorta piercing central tendon of diaphragm at T8

Question 12

What is the function of the IVC?

Answer 12

takes blood from the body below the diaphragm to the right atrium of the heart

Question 13

What forms the IVC?

Answer 13

• left and right common iliac veins

- median sacral vein

Question 14

What veins drain to the IVC?

Answer 14

• hepatic veins
• right inferior phrenic vein
• right suprarenal vein
• both renal veins
• right gonadal vein
• lumbar veins
• asymmetrical
  (left suprarenal and gondal vein drain to left renal)

Question 15

What forms the portal venous system?

Answer 15

• splenic vein
• superior mesenteric vein
• formed posterior to neck of pancreas

Question 16

Describe the anatomical position of the portal venous system

Answer 16

• crosses first part of duodenum and enters lesser omentum
• runs cranially in hepatoduodenal ligament towards porta hepatis
• then divides into left and right terminal branches

Question 17

What is the function of the hepatic portal system?

Answer 17

• hepatic portal vein drains venous blood between lower third of oesophagus to distal hald of anal canal
• also spleen pancreas and gallbladder
• goes to liver and branches supply sinusoids (where it mixes with oxygenated blood from hepatic artery proper) which takes blood to central veins
• central veins go to hepatic veins which go to IVC

Question 18

What is portal hypertension and its implications?

Answer 18

• elevation of blood pressure in the portal system
• can result in reversal of blood flow
• causes a larger volume of blood to enter the anastomotic collaterals instead which can lead to varicose veins

Question 19

What are the potential causes of portal hypertension?

Answer 19

• dimished or blocked flow in hepatic portal vein
• pre-hepatic causes (portal vein/splenic vein thrombosis)
• hepatic causes (tumours, cirrhosis, parasite infections)
• post-hepatic causes (cardiac disease, hepatic vein/IVC thrombosis)

Question 20

What are the porto-systemic (porto-caval) anastomoses?

Answer 20

• oesophageal varices
• rectal varices
• caput medusae
• posterior abdominal wall

Question 21

What are the porto and caval components of the oesophageal varices?

Answer 21

• porto: at lower 1/3rd oesophagus branches of left gastric (from portal vein)
• caval: oesophageal veins drain middle 1/3rd oesophagus to azygos veins to SVC

Question 22

What are the porto and caval components of the rectal varices?

Answer 22

• porto: halfway down anal canal, superior rectal (from portal vein) that drains upper half of anal canal
• caval: middle and inferior rectal veins that drain to internal iliac and internal pudendal veins to IVC

Question 23

What are the porto and caval components of caput medusae?

Answer 23

• porto: around the umbilicus para-umbilical veins (from left branch of portal vein)
• caval: epigastric veins (from femoral, external iliac, internal thoracic and axillary veins to IVC and SVC)

Question 24

What are the porto and caval components of the posterior abdominal wall anastomoses?

Answer 24

• porto: veins from secondarily retroperitoneal organs

- caval: veins of body wall