Anatomy of the liver

Question 1

Liver topography

Answer 1

Largest gland in the body

Wedge shaped reddish brown organ

Located below the diaphragm, mostly the right hypochondrium and epigastrium

Question 2

Main liver functions

Answer 2

Detoxification

Protein synthesis

Production of bile- accessory GI organ

Glycogen storage

Question 3

Anterior view of the liver

Answer 3

Divided into two main lobes

Left and right

Question 4

Posterior view of the liver

Answer 4

Two other lobes

Quadrate and caudate

Question 5

Liver gross anatomy

Answer 5

Surface covered by peritoneum except bare area where it connects with diaphragm

Flaciform and lesser omentum ligaments separate left and right lobes

Porta hepatis divides the quadrate and caudate lobes

Question 6

Peritoneal folds

Answer 6

Falciform ligament: links diaphragm to upper surface ligamentum teres at lower end

Round ligament: obliterated left umblical vein, extends to umbilicus

Coronary ligaments: links diaphragm to liver

Lesser omentum: links liver to stomach

Question 7

Lesser omentum

Answer 7

From lesser curvature stomach to porta hepatis

Has a free margin

Encloses: hepatic artery, portal vein, bile duct, lymph vessels

Close to the stomach it encloses the gastric arteries and veins

Question 8

Blood supply to the gut

Answer 8

Resort to embryological terms: foregut, midgut, hindgut

Each division with specific artery

All midline branches of the abdominal aorta

Question 9

Blood supply to the liver

Answer 9

Coeliac artery: left gastric, splenic, hepatic

T12/L1 level

Also supplies duodenum and pancreas

No similarly named vein

Question 10

Hepatic artery variations

Answer 10

Seen in 40-45% of people

Most common cases:

• right hepatic artery replaced to the SMA
• left hepatic artery replaced to the left gastric artery
• trifurcation of the common hepatic artery ( right hepatic artery, left hepatic artery, gastroduodenal artery)

Question 11

Liver- functional anatomy

Answer 11

Performs a broad range of processes

Metabolism: portal system

Production and secretion of bile

Divided into lobes and segments to perform these

Question 12

Liver and metabolism

Answer 12

Porta hepatis

• at hilum of liver
• deep fissure- 5cm
• entry/ exit pont for: hepatic portal vein, hepatic artery proper, common hepatic duct, nerves and lymphatics
• once in: branching of vessels
• division of liver into lobes and segments

Question 13

Hepatic artery

Answer 13

Oxygenated blood

Question 14

Portal vein (superior mesenteric and splenic)

Answer 14

Deoxygenated blood

Nutrients

Drugs

Toxins

Question 15

Liver lobule

Answer 15

Liver anatomic lobes are subdivided into segments

Branches of hepatic artery and portal vein carry blood into sinusoids

Branches of bile duct accompany those of hepatic artery and portal vein

All three structure called portal triad and supply each segment

Question 16

Lobules

Answer 16

Each lobe contains several lobules

The functional units of the liver

Hexagon shaped

Contain hepatocytes (60% liver cells)

Hepatocytes also secrete bile

Portal triads at corners

Question 17

Hepatocytes- metabolic functions

Answer 17

Synthesis and release plasma proteins into blood; albumin; clotting factors complement cascade components

Deaminates amino acids- urea into blood

Bilirubin to bile pigments

Bile salts- emulsification of fats

Question 18

Venous drainage of the liver

Answer 18

Mixed blood from the two source in the sinusoids passes through hepatocytes and into the central vein

Central vein is found at the centre of a hepatic lobule

Central veins then drain into the sublobular vein

Sublobular veins then drain into hepatic veins

Question 19

Portal systemic anastomosis

Answer 19

Communications between some branches of the portal and systemic systems

Portocaval anastomosis

Important if portal vein blocked or passage via liver meets resistance- portal hypertension

Allow collateral return of blood to heart without which subject would die

Question 20

Anastomosis in abdominal part of oesophagus

Answer 20

Left gastric tributaries with oesophageal branches azygos

Question 21

Anastomosis in anal canal

Answer 21

Superior rectal anastomoses with middle inferior rectal

Question 22

Anastomosis in umbilicus

Answer 22

Paraumbilical veins with epigastric veins

Question 23

Anastomosis in veins of colon, duodenum, pancreas, liver

Answer 23

With renal, lumbar and phrenic

Question 24

Portal hypertension

Answer 24

Common clinical condition

Obstruction of portal vein

Pressure rises- hypertension

Anastomoses between portal and systemic means backflow to heart then lungs

Varicoses

Caput medusa; oesophageal varices

Question 25

Portacaval shunt

Answer 25

Reduction of hypertension

Divert blood from portal to systemic

Blood diverted from portal to IVC

Portal vein conveys 70% blood to liver

Largerly been abandoned since the advent of TIPS

Question 26

TIPS

Answer 26

Transjugular intrahepatic portosystemic shunting

Question 27

Bile

Answer 27

Secreted by hepatocytes into bile canaliculi

50ml/ hour

Closed sphincter oddi to duodenum-bile flos to gall bladder to be stored and concentrated

Right and left hepatic ducts- relevant lobes

Emerge from porta- unite to form common hepatic duct

Question 28

Lymphatic drainage

Answer 28

Liver produces vast amount of lymph

Lymph nodes in porta hepatis

Pass to coeliac nodes

Drain to cisteran chyli

Question 29

Liver trauma

Answer 29

Closely related to lower ribs

Fractured ribs/ penetrating wounds

High vascularisation- severe haemorrhage

Remove portions due to segmental nature liver vessels/ ducts supplying it

• liver biopsies
• metastatic spread
• cirrhosis