Session 3: The Liver And Gallbladder

Question 1

Where is the liver?

Answer 1

lies in the right upper quadrant and epigastrium of the abdomen.

Question 2

What are the surfaces of the liver?

Answer 2

two surfaces:
• The diaphragmatic surface lies anterosuperior
• The visceral surface lies posteroinferior

Question 3

What is the liver covered by?

Answer 3

The liver is mostly, but not entirely, covered by visceral peritoneum.

Question 4

Where are the lobes of the liver?

Answer 4

The liver is composed of two anatomical lobes – a large right lobe and a small left lobe. They are separated by the falciform ligament, which connects the anterior surface of the liver to the internal aspect of the anterior abdominal wall. Two accessory lobes, the caudate and quadrate lobes, are located on the posteroinferior surface. These lobes do not represent the internal, functional organisation of the liver.

Question 5

What is the liver connected to?

Answer 5

• diaphragm by the coronary and triangular ligaments
• anterior abdominal wall by the falciform ligament
• stomach and duodenum by the lesser omentum.

Question 6

Where is the portal triad?

Answer 6

The hepatic artery, hepatic portal vein and the bile duct run together as the portal triad in the free edge of the lesser omentum. The portal triad and the free edge of the lesser omentum form the anterior boundary of the epiploic foramen; the entrance into the lesser sac (which lies posterior to the stomach).

Question 7

What are the recesses related to the liver?

Answer 7

There are two recesses related to the liver:
• The hepatorenal recess lies between the right kidney and the posterior (visceral) surface of the right side of the liver. Fluid flows into this space in the supine position.
• The left and right subphrenic recesses lie either side of the falciform ligament, between the anterosuperior surface of the liver and the diaphragm.

Question 8

How is the liver developed?

Answer 8

Development of the Liver
The liver develops from the embryological foregut. It grows from a tissue bud that develops in the ventral mesentery – a peritoneal fold in the upper abdomen that connects the stomach to the anterior abdominal wall. As the liver grows and migrates to the right side of the abdomen, its peritoneal attachments are pulled with it. The remains of the ventral mesentery form the lesser omentum and the falciform ligament. The peritoneal attachments of the liver anchor it to surrounding structures, including the diaphragm superior to it.

The free edge of the falciform ligament contains the round ligament of the liver (the ligamentum teres). It is the remnant of the umbilical vein, which, in the foetus, carries oxygenated blood from the placenta to the foetus. Another embryological remnant, the ligamentum venosum, lies on the posterior surface of the liver, in the groove between the caudate lobe and the left lobe of the liver. It is the remains of the ductus venosus, which in foetal life diverts blood from the umbilical vein to the IVC, thus shunting oxygen-rich blood to the heart and bypassing the liver.

Question 9

What supplies the liver?

Answer 9

The liver is supplied by the right and left hepatic arteries. These branches ultimately derive from the coeliac trunk.
• The coeliac trunk gives rise to the left gastric, splenic, and common hepatic arteries.
• The common hepatic artery gives rise to the gastroduodenal artery; after this point, the common hepatic artery is called the hepatic artery proper (HAP).
• The hepatic artery proper bifurcates into right and left hepatic arteries, which enter the liver at the porta hepatis.

Question 10

What is the venous drainage of the liver?

Answer 10

Venous blood exits the liver via two or three large hepatic veins that lie within the liver – they are not visible external to the liver. They unite with the inferior vena cava as it passes posterior to the liver.

Question 11

What is the venous drainage of the liver?

Answer 11

Venous blood exits the liver via two or three large hepatic veins that lie within the liver – they are not visible external to the liver. They unite with the inferior vena cava as it passes posterior to the liver.

Question 12

What is the difference between the hepatic vein and the hepatic portal vein?

Answer 12

the hepatic veins with the hepatic portal vein. To be clear:
• Nutrient-rich venous blood that leaves the gut is transported to the liver via the hepatic portal vein, which receives blood from the superior and inferior mesenteric veins and the splenic vein.
• Venous blood leaves the liver via the hepatic veins and enters the inferior vena cava.

Question 13

What is the hepatic plexus?

Answer 13

The liver is served by the hepatic plexus, which is formed of parasympathetic fibres from the vagus nerves and sympathetic fibres. These fibres follow the paths of the hepatic vessels and ducts of the biliary tree. Because the liver is a foregut derivative, pain arising from it is referred to the epigastric region.

Question 14

What does the gallbladder do?

Answer 14

The gallbladder stores and concentrates bile. It lies on the posteroinferior (visceral) surface of the liver and lies close to the duodenum. The gallbladder has three parts, the fundus, the body, and the neck.

Question 15

What is the structure of the gallbladder?

Answer 15

The body forms the main part of the gallbladder which sits in the gallbladder fossa on the visceral surface of the liver. It tapers towards the neck, which communicates with the cystic duct. The fundus is the rounded end of the gallbladder, which typically extends to the inferior border of the liver. The surface marking of the fundus of the gallbladder is at the tip of the 9th costal cartilage, at the point where the right midclavicular line intersects the right costal margin.

Question 16

What is the biliary tree?

Answer 16

Bile is continuously produced by hepatocytes in the liver and is first excreted into small channels called bile canaliculi. The canaliculi drain into bile ducts of increasing calibre, which ultimately converge to form right and left hepatic ducts that exit the liver at the porta hepatis.
• The left and right hepatic ducts converge to form the common hepatic duct.
• The common hepatic duct receives the cystic duct from the gallbladder. Distal to this point, the duct is called the common bile duct (or sometimes just simply the bile duct).
• The common bile duct runs in the free edge of the lesser omentum.
• The common bile duct descends posterior to the superior part of the duodenum and posterior to the head of the pancreas.
• The common bile duct enters the duodenum.

Question 17

What happens to bile not needed for digestion?

Answer 17

If bile leaving the liver is not needed for digestion, it enters the gallbladder via the cystic duct. When needed, bile flows from the gallbladder, via the cystic duct, to the common bile duct and duodenum. The spiral fold (spiral valve) lies at the junction between the gallbladder neck and the cystic duct.

Question 18

What is the supply of the gallbladder?

Answer 18

Blood supply is via the cystic artery, which typically arises from the right hepatic artery (variation exists).
• The gallbladder is drained by cystic veins that pass directly into the liver or join the hepatic portal vein

Question 19

What is the gallbladder innervated by?

Answer 19

The gallbladder is innervated by parasympathetic and sympathetic fibres.
• Visceral afferents from the gallbladder return to the CNS with the sympathetic fibres. Visceral pain from the gallbladder enters spinal cord levels T5 – T9 and is therefore referred to (i.e. felt in) the epigastrium.
• Gallbladder pain may also be referred to the right shoulder if gallbladder pathology (e.g. inflammation) irritates the diaphragm. The diaphragm is innervated by the phrenic nerve (C3-5). Spinal cord segments C3-5 also receive somatic sensory information from the skin over the shoulder. Therefore gallbladder pathology involving the diaphragm may be felt in the right shoulder.
• If gallbladder pathology irritates the parietal peritoneum, which is innervated by somatic nerves, pain is well localised to the right hypochondrium.

Question 20

What is hepatomegaly?

Answer 20

Hepatomegaly
Hepatomegaly is enlargement of the liver. Causes include hepatitis (inflammation of the liver from various causes), malignancy, and heart failure. When the liver is enlarged, its inferior border becomes palpable inferior to the right costal margin.

Question 21

What is hepatomegaly?

Answer 21

Hepatomegaly
Hepatomegaly is enlargement of the liver. Causes include hepatitis (inflammation of the liver from various causes), malignancy, and heart failure. When the liver is enlarged, its inferior border becomes palpable inferior to the right costal margin.

Question 22

What is liver metastases?

Answer 22

Liver metastases
Although primary cancer of the liver does occur, most cancers of the liver are metastases from cancer elsewhere in the body. Because venous blood from the gut passes through the liver, bowel cancers often metastasize to the liver.

Question 23

What is cirrhosis of the liver?

Answer 23

Cirrhosis of the liver
Cirrhosis is sometimes referred to as ‘scarring’ of the liver. It is caused by chronic excess alcohol consumption, chronic infection with hepatitis B or C, or a build-up of fat in the liver. Hepatocytes are destroyed and replaced with fibrous tissue. The liver becomes shrunken, hard, and nodular. Loss of hepatocytes impairs the function of the liver and liver failure may ultimately result.

Question 24

What is portal hypertension and portosystemic anastamoses?

Answer 24

Portal hypertension and portosystemic anastomoses
Portal hypertension is high blood pressure in the portal venous system. It results when blood flow through the liver and portal vein is obstructed (e.g. in cirrhosis of the liver). Portosystemic anastomoses are communications between veins draining to the systemic circulation and veins draining to the portal circulation. For example, in the distal oesophagus, venous blood drains into both the systemic veins (via the azygos) and into the portal system (via the gastric veins). If flow in the portal system is obstructed, pressure in the portal system increases and blood is diverted from the portal veins into the systemic veins. The systemic veins become distended and varicose (in the oesophagus these are called oesophageal varices) and prone to rupture, which can result in catastrophic bleeding.

Question 25

What is portal hypertension and portosystemic anastamoses?

Answer 25

Portal hypertension and portosystemic anastomoses
Portal hypertension is high blood pressure in the portal venous system. It results when blood flow through the liver and portal vein is obstructed (e.g. in cirrhosis of the liver). Portosystemic anastomoses are communications between veins draining to the systemic circulation and veins draining to the portal circulation. For example, in the distal oesophagus, venous blood drains into both the systemic veins (via the azygos) and into the portal system (via the gastric veins). If flow in the portal system is obstructed, pressure in the portal system increases and blood is diverted from the portal veins into the systemic veins. The systemic veins become distended and varicose (in the oesophagus these are called oesophageal varices) and prone to rupture, which can result in catastrophic bleeding.

Question 26

What can gall stones cause?

Answer 26

Gallstones, biliary colic, and cholecystitis
Gallstones are common in the UK population. They are mostly composed of cholesterol. They are often asymptomatic but cause symptoms when they migrate into the biliary tree and lodge there. When a gallstone lodges in the cystic duct, contraction of the gallbladder against it causes severe pain termed biliary colic. If the stone moves back into the gallbladder, the pain eases. If it does not, and the stone becomes stuck, it blocks the flow of bile into the cystic duct and the gallbladder becomes inflamed (cholecystitis). Cholecystectomy is removal of the gallbladder. It is usually performed laparoscopically

Question 27

What is the location of the coeliac trunk?

Answer 27

The coeliac trunk leaves the anterior aspect of the aorta at the level of T12. It gives rise to three major branches:
• The left gastric artery – supplies the distal oesophagus and lesser curvature of the stomach.
• The common hepatic artery – branches supply the liver, stomach, and duodenum.
• The splenic artery – branches supply the stomach, pancreas, and spleen.

Question 28

What is the duodenum?

Answer 28

The duodenum is the first and shortest part of the small intestine. It is continuous proximally with the pylorus of the stomach and distally with the jejunum. The pyloric sphincter regulates gastric emptying into the duodenum.
• Most of the duodenum is retroperitoneal.
• The duodenum forms a C-shape that cups the head of the pancreas.
• The duodenum is described in four parts. These are the superior (first), descending (second), the inferior (third) and the ascending (fourth) parts.
• The common bile duct, gastroduodenal artery and the hepatic portal vein lie posterior to the first part of the duodenum.
• The superior mesenteric artery lies anterior to the third part.
• The fourth part meets the jejunum at the duodenojejunal flexure.
• Approximately halfway along the internal wall of the duodenum is a small elevation called the major duodenal papilla (papilla = nipple-like). This marks the point at which bile and digestive pancreatic secretions (‘pancreatic juice’) enter the duodenum. We will learn more about this shortly.

Question 29

What is the supply of the duodenum?

Answer 29

Blood Supply of the Duodenum
The first half of the duodenum is derived from the foregut and is supplied by branches of the coeliac trunk (the artery of the foregut). The second half is derived from midgut and is supplied by branches of the superior mesenteric artery (the artery of the midgut). Arterial branches that supply the duodenum are derived from the:
• gastroduodenal artery (from the common hepatic artery and hence the coeliac trunk)
• inferior pancreaticoduodenal arteries (from the superior mesenteric artery)
Veins follow the arteries and are tributaries of the hepatic portal vein.

Question 30

Where is the pancreas located?

Answer 30

The pancreas lies horizontally on the posterior abdominal wall at the level of L1 and is retroperitoneal. It does not have a capsule so in the cadaver its surface appears ‘bumpy’ rather than smooth.

Question 31

What is the pancreas formed from?

Answer 31

It forms from dorsal and ventral pancreatic buds which fuse during development.
• It is composed of four parts: the head, the neck, the body, and the tail.
• The uncinate process is a hook-like projection of the head of the pancreas.
• The head is cupped by the C-shaped duodenum and the tail extends to the hilum of the spleen.
• The pancreas forms part of the posterior wall of the lesser sac.
• The splenic artery runs towards the spleen embedded in the upper border of the pancreas. The splenic vein lies posterior to the pancreas.
• The main pancreatic duct and the accessory pancreatic duct run within the substance of the pancreas.

Question 32

What is the function of the pancreas?

Answer 32

Function of the Pancreas
The pancreas has an endocrine and an exocrine function. It synthesizes and secretes insulin and glucagon. Insulin is released in response to high levels of glucose in the blood. The pancreas also produces pancreatic juice that contains digestive enzymes. Pancreatic juice is transported through main pancreatic duct and the accessory pancreatic duct to the duodenum. The main and accessory pancreatic ducts usually communicate with each other.

Question 33

What is the relationship between the main pancreatic duct and the bile duct?

Answer 33

Relationship Between the Main Pancreatic Duct and the Bile Duct
The duodenum receives:
• bile from the liver and gallbladder via the common bile duct
• pancreatic juice from the pancreas via the main and accessory pancreatic ducts.

The common bile duct and main pancreatic duct merge at the hepatopancreatic ampulla (ampulla = dilation). The hepatopancreatic ampulla opens into the second part of the duodenum at the major duodenal papilla, which is located on the internal wall of the duodenum, about halfway along its length. The hepatopancreatic ampulla is surrounded by smooth muscle - the hepatopancreatic sphincter (sometimes called the sphincter of Oddi). Contraction of the sphincter prevents reflux of duodenal contents into the common bile duct and main pancreatic duct.

The accessory pancreatic duct empties pancreatic juice into the duodenum at the minor duodenal papilla, which lies just proximal to the major duodenal papilla.

Question 34

What is the blood supply of the pancreas?

Answer 34

Blood Supply of the Pancreas
The pancreas is supplied by blood vessels derived from the coeliac trunk and blood vessels derived from the superior mesenteric artery:
• The splenic artery, a major branch from the coeliac trunk, runs along the upper border of the pancreas and gives rise to pancreatic arteries.
• The gastroduodenal artery (from the common hepatic artery and hence the coeliac trunk) gives rise to the superior pancreaticoduodenal arteries that supply the pancreas.
• The superior mesenteric artery gives rise to the inferior pancreaticoduodenal arteries that supply the pancreas.
Veins follow the arteries. The splenic vein drains the pancreas and unites with the superior mesenteric vein to form the hepatic portal vein posterior to the neck of the pancreas.

Question 35

Where is the spleen?

Answer 35

The spleen is a haematopoietic and lymphoid organ that lies in the left upper quadrant, protected by ribs 9 - 11. It is covered with visceral peritoneum. It has several functions that include the breakdown of old red blood cells, the storage of red blood cells and platelets, and various immune responses, including production of IgG.

Question 36

What is the spleen composed of?

Answer 36

The spleen has two surfaces and four borders:

• the diaphragmatic surface lies adjacent to the diaphragm
• the visceral surface lies in contact with the stomach, left kidney and colon. The splenic vessels enter and exit the spleen at the hilum on the visceral surface
• the anterior and superior borders are typically notched
• the posterior and inferior borders are smooth.
A normal sized spleen is not palpable below the costal margin. If it is palpable, it is enlarged by at least three times its normal size.

Question 37

What is the blood supply of the spleen?

Answer 37

The spleen is supplied by the splenic artery, a branch of the coeliac trunk. The splenic artery runs along the superior border of the pancreas, embedded within it. The artery divides into approximately five branches at the hilum.
Venous drainage is via the splenic vein, which runs posterior to the pancreas. It unites with the superior mesenteric vein to form the hepatic portal vein.

Question 38

What is a duodenal ulcer?

Answer 38

Duodenal (peptic) ulcers are most common in the first part of the duodenum. A duodenal ulcer here may erode the duodenal wall and the gastroduodenal artery, which lies posterior to the first part of the duodenum, resulting in severe intra-abdominal bleeding.

Question 39

What is pancreatitis?

Answer 39

Pancreatitis
Inflammation of the pancreas may be chronic or acute. Acute pancreatitis is a life-threatening condition. There are many causes, but in the UK, it is most commonly due to excess alcohol intake or impaction of a gallstone at the hepatopancreatic ampulla. In gallstone pancreatitis, impaction of the gallstone prevents pancreatic juice from leaving the pancreas and it starts to break down the pancreas (autolysis). It is extremely painful, typically causing pain that radiates to the back.

Question 40

What is pancreatitis?

Answer 40

Pancreatitis
Inflammation of the pancreas may be chronic or acute. Acute pancreatitis is a life-threatening condition. There are many causes, but in the UK, it is most commonly due to excess alcohol intake or impaction of a gallstone at the hepatopancreatic ampulla. In gallstone pancreatitis, impaction of the gallstone prevents pancreatic juice from leaving the pancreas and it starts to break down the pancreas (autolysis). It is extremely painful, typically causing pain that radiates to the back.

Question 41

What is pancreatic cancer?

Answer 41

Pancreatic cancer
Cancer can affect any part of the pancreas and typically causes pain that radiates to the back. When it affects the head of the pancreas, it can obstruct the flow of bile in the bile duct. This leads to an accumulation of bile pigments in the blood and results in jaundice (yellowing of the skin).

Question 42

What is diabetes mellitus?

Answer 42

Diabetes mellitus
Diabetes mellitus results when the insulin-producing cells of the pancreas no longer produce insulin (or produce inadequate amounts). This leads to sustained high blood glucose levels which are detrimental to many tissues of the body and are ultimately fatal if not controlled. Some patients develop diabetes secondary to pancreatitis.

Question 43

What is splenomegaly?

Answer 43

Splenomegaly
Enlargement of the spleen is splenomegaly. Causes include infection (e.g. infectious mononucleosis, malaria), haematological malignancy (e.g. leukaemia) and portal hypertension. When the spleen enlarges, it does so towards the midline, in the direction of the right iliac fossa, because the phrenicocolic ligament prevents its direct descent towards the left iliac fossa.

Question 44

What is a splenic rupture?

Answer 44

The spleen is soft and highly vascular and is therefore vulnerable to blunt abdominal trauma or rib fractures that may puncture the spleen. Splenic haemorrhage is life-threatening and is managed by removing the spleen (splenectomy). The spleen is not essential for life, although patients are more prone to some bacterial infections after splenectomy.

Question 45

What protects the liver?

Answer 45

The liver is protected by the ribs and moves inferiorly with inspiration – the lowermost part of the liver may be palpable below the right costal margin in inspiration.

Question 46

What does the liver produce?

Answer 46

All the products of digestion, except lipids, are transported to the liver from the gut via the hepatic portal vein. The liver also produces bile, which is transported to the gallbladder for storage.

Question 47

What does bile do?

Answer 47

Bile emulsifies lipids in the chyme entering the duodenum from the stomach.

Question 48

Which regions of the liver are not covered by peritoneum?

Answer 48

The regions not covered by peritoneum are the:
• bare area of the liver – a region on the posterior surface that lies in contact with the diaphragm
• the region where the gallbladder lies in contact with the liver
• region of the porta hepatis – where hepatic blood vessels and ducts of the biliary system enter and exit the liver (the equivalent of the hilum of the lung).

Question 49

What is the liver organised into?

Answer 49

Internally the liver is organised into eight functional segments. Each segment is served by its own branch of the hepatic artery and portal vein, and by its own hepatic duct.