W3: Liver, pancreas

Question 1

Position of liver

Answer 1

Right hypochondrium, epigastric region & left hypochondrium

Question 2

Peritoneal attachments of the liver

Answer 2

Falciform ligament
Lesser omentum

Question 3

Were is there no peritoneal coverage of the liver?

Answer 3

Where the gallbladder is
Known as the bare area

Question 4

Lobes of liver

Answer 4

4 lobes
Right - deep to the 7th-11th ribs
Left - epigastric and left hypochondriac regions
Caudate
Quadrate

Question 5

Which anterior lobe is larger?

Answer 5

Right

Question 6

What are the right and left lobes separated by?

Answer 6

Falciform ligament

Question 7

What separates the caudate and quadrate lobes?
What runs through this?

Answer 7

Porta hépatis
The portal triad runs through it - hepatic artery proper, hepatic portal vein and common hepatic duct

Question 8

In surgery, how is the liver more commonly defined?

Answer 8

In surgery, it is more common to refer to the 8 functionally independent segments of the liver, the boundaries of which are determined by vascular supply and biliary drainage.

Question 9

Where is the gallbladder

Answer 9

Gallbladder fossa - inferior surface of liver - between quadrate and right lobes

Question 10

What is the function of the gallbladder?

Answer 10

Store ultra-concentrate bile prior to its release during meals

Question 11

Describe the hepatic vasculature at point of entry into the liver

Answer 11

The portal vein, hepatic artery proper and common hepatic duct bifurcate into right and left branches - subsequently subdivide to form secondary branches that supply the medial and lateral parts of each lobe. Finally, tertiary branches supply each of the individual segments of the liver.

Question 12

What proportion of blood does the hepatic portal vein supply? What does the rest?

Answer 12

Around 75%
Hepatic artery proper

Question 13

What vessels supply what proportion of the oxygen to the liver?

Answer 13

50% hepatic portal vein
50% hepatic artery proper

Question 14

What is the liver drained by?

Answer 14

Hepatic veins which pass to the IVC on the posterior surface of the liver (short)

Question 15

Liver Cirrhosis

Answer 15

Cirrhosis is the end-stage of liver fibrosis, which results in disorganised parenchymal architecture and impairment of liver function. Cirrhosis may be caused by chronic alcoholism or chronic hepatitis B/C infec- tion. Biliary injury such as bile duct obstruction, primary biliary cirrhosis and primary sclerosing cholangitis may also result in liver cirrhosis. Symptoms are typically non-specific, and may include weight loss, fatigue and anorexia. With declining liver function, patients may become jaundiced and have ascites. Cirrhosis is considered irreversible and requires liver transplantation for a cure.

Liver may be smaller

Question 16

Portal Hypertension and Porto-Systemic Anastomoses

Answer 16

Portal hypertension is the most common, serious complication of liver cirrhosis, and may cause GI bleed- ing through oesophageal/rectal varices at the sites of porto-systemic anastomoses, ascites, pulmonary hy- pertension and kidney injury. Portal hypertension may cause the re-canalisation of the obliterated paraum- bilical veins within the ligamentum teres and abdominal wall, resulting in the appearance of caput medusae around the umbilicus.

Question 17

Falciform ligament

Answer 17

a remnant of the ventral mesentery of the foetus. Attaches the anterior surface of the liver to the anterior abdominal wall, dividing the liver into the left and right lobes. Its free edge contains the ligamentum teres (round ligament), a remnant of the umbilical vein.

Question 18

Coronary ligament

Answer 18

attaches the superior surface of the liver to the inferior surface of the diaphragm. The area between the anterior and posterior folds of the coronary ligament is the bare area of the liver.

Question 19

Triangular ligaments

Answer 19

• Left triangular ligament – attaches the posterior part of the superior surface of the left lobe of the liver to the diaphragm.
  
  • Formed by the union of the anterior and posterior layers of the coronary ligament at the apex of the liver and attaches the left lobe of the liver to the diaphragm.
• Right triangular ligament – passes from the posterior part of the bare area on the right side to the dia- phragm.
  
  • Formed in the same way

Question 20

Lesser omentum

Answer 20

passes from the lesser curvature of the stomach to the inferior surface of the liver (also first part of duodenum). The portal triad is found within the free edge of the lesser omentum.

It consists of the hepatoduodenal ligament (extends from the duodenum to the liver) and the hepatogastric ligament (extends from the stomach to the liver). The hepatoduodenal ligament surrounds the portal triad.

Question 21

How is the liver attached to the IVC?

Answer 21

Hepatic veins and fibrous tissue

Question 22

Which lobe do the accessory lobes arise from?

Answer 22

Right

Question 23

Where is the caudate lobe?

Answer 23

located on the upper aspect of the visceral surface. It lies between the inferior vena cava and a fossa produced by the ligamentum venosum (a remnant of the fetal ductus venosus).

Question 24

Where does the quadrate lobe lie?

Answer 24

located on the lower aspect of the visceral surface. It lies between the gallbladder and a fossa produced by the ligamentum teres (a remnant of the fetal umbilical vein).

Question 25

Describe microstructure

Answer 25

Each anatomical lobule is hexagonal-shaped and is drained by a central vein. At the periphery of the hexagon are three structures collectively known as the portal triad:

Arteriole – a branch of the hepatic artery entering the liver.

Venule – a branch of the hepatic portal vein entering the liver.

Bile duct – branch of the bile duct leaving the liver.

The portal triad also contains lymphatic vessels and vagus nerve (parasympathetic) fibres.

Question 26

What is a liver sinusoid?

Answer 26

A liver sinusoid is a type of capillary known as a sinusoidal capillary, discontinuous capillary or sinusoid, that is similar to a fenestrated capillary, having discontinuous endothelium that serves as a location for mixing of the oxygen-rich blood from the hepatic artery and the nutrient-rich blood from the portal vein

Question 27

What is the hepatic artery proper derived from?

Answer 27

Coeliac trunk

Question 28

What drains into the hepatic portal vein?

Answer 28

Superior mesenteric

Inferior mesenteric

Splenic

Splenic and superior fuse

Inferior goes to either of the two/or both - depending on the person

Question 29

Liver Metastases

Answer 29

The most common form of liver tumour are metastatic deposits from primary tumours located else- where. 50% of all metastatic lesions within the liver are derived from GI tract malignancies. Other com- mon primary tumours metastasising via the blood to the liver include the breast, lung, kidney and ovaries. The liver is a common site of metastatic disease due to its extensive, dual blood supply and relatively porous sinusoids, allowing the transport of malignant cells into the liver parenchyma.

Question 30

Innervation of liver

Answer 30

The parenchyma of the liver is innervated by the hepatic plexus, which contains sympathetic (coeliac plexus) and parasympathetic (vagus nerve) nerve fibres. These fibres enter the liver at the porta hepatis and follow the course of branches of the hepatic artery and portal vein.

Glisson’s capsule, the fibrous covering of the liver, is innervated by branches of the lower intercostal nerves. Distension of the capsule results in a sharp, well localised pain.

Question 31

Lympathic drainage of liver

Answer 31

The lymphatic vessels of the anterior aspect of the liver drain into hepatic lymph nodes. These lie along the hepatic vessels and ducts in the lesser omentum, and empty in the colic lymph nodes which in turn, drain into the cisterna chyli.

Lymphatics from the posterior aspect of the liver drain into phrenic and posterior mediastinal nodes, which join the right lymphatic and thoracic ducts.

Question 32

What is bile released in response to?

Answer 32

CCK

Question 33

Anatomical structure of bile duct

(remember mucosal fold)

Answer 33

Fundus – the rounded, distal portion of the gallbladder. It projects into the inferior surface of the liver in the mid-clavicular line.

Body – the largest part of the gallbladder. It lies adjacent to the posteroinferior aspect of the liver, transverse colon and superior part of the duodenum.

Neck – the gallbladder tapers to become continuous with the cystic duct, leading into the biliary tree.

The neck contains a mucosal fold, known as Hartmann’s Pouch. This is a common location for gallstones to become lodged, causing cholestasis.

Question 34

What does the biliary tree allow?

Answer 34

newly synthesised bile from the liver to be concentrated and stored in the gallbladder (prior to release into the duodenum).

Question 35

Discuss biliary tree from liver

Answer 35

Bile is initially secreted from hepatocytes and drains from both lobes of the liver via canaliculi, Canal of Hering -> intralobular ducts and collecting ducts into the left and right hepatic ducts. These ducts amalgamate to form the common hepatic duct, which runs alongside the hepatic vein.

Question 36

What happens to the common hepatic duct as it descends?

Answer 36

Is joined by the cystic duct – which allows bile to flow in and out of the gallbladder for storage and release. At this point, the common hepatic duct and cystic duct combine to form the common bile duct.

The common bile duct descends and passes posteriorly to the first part of the duodenum and head of the pancreas. Here, it is joined by the main pancreatic duct, forming the hepatopancreatic ampulla (commonly known as the ampulla of Vater) – which then empties into the duodenum via the major duodenal papilla

Question 37

What is the major duodenal papilla regulated by?

Answer 37

Sphincter of Oddi

Question 38

Arterial supply of gallbladder

Answer 38

The arterial supply to the gallbladder is via the cystic artery – a branch of the right hepatic artery (which itself is derived from the common hepatic artery, one of the three major branches of the coeliac trunk).

common hepatic -> right hepatic -> cystic artery

Question 39

Venous drainage gallbladder

Answer 39

Venous drainage of the neck of the gallbladder is via the cystic veins, which drain directly into the portal vein. Venous drainage of the fundus and body of the gallbladder flows into the hepatic sinusoids.

Question 40

Innervation of gallbladder

Answer 40

The gallbladder receives parasympathetic, sympathetic and sensory innervation.

The coeliac plexus carries sympathetic and sensory fibres, while the vagus nerve delivers parasympathetic innervation.

Parasympathetic stimulation produces contraction of the gallbladder, and the secretion of bile into the cystic duct due to relaxation of the sphincter of Oddi. The majority of this response however, is mediated by circulating cholecystokinin as part of the gustatory response.

Question 41

Gallbladder lymph drainage

Answer 41

Lymph from the gallbladder drains into the cystic lymph nodes, situated at the gallbladder neck.

The cystic nodes then empty into the hepatic lymph nodes, and ultimately, the coeliac lymph nodes.

Question 42

Calot’s Triangle

Answer 42

The cystic duct, common hepatic duct and inferior edge of the liver creates Calot’s Triangle, an anatomical re- gion demarcating the location of the cystic artery and Lund’s node, the sentinel lymph node of the gallbladder.

Contents:

• Right hepatic artery – formed by the bifurcation of the proper hepatic artery into right and left branches.
• Cystic artery – typically arises from the right hepatic artery and traverses the triangle to supply the gall bladder.
• Lymph node of Lund – the first lymph node of the gallbladder.
• Lymphatics

Question 43

What happens if gallbladder becomes infected

Answer 43

If the gallbladder becomes infected, as in cholecystitis, involvement of the parietal peritoneum results in well-localised, sharp pain within the right upper quadrant which may be referred, via the phrenic nerve, to the C4 dermatome, due to diaphragmatic peritoneal irritation.

Question 44

Gallstones

Answer 44

Around 15-20% of people have gallstone-related problems during their lifetime. Risk factors include in- creased age, obesity and being female. 80% of gallstones are of the cholesterol type, whereas 20% are formed from bilirubin calcium salts. Gallstones can block the biliary tree at various points, and can give rise to variety of symptoms:

Biliary colic – caused most commonly by gallstones lodging within Hartmann’s pouch, an out-pouching at the junction of the neck of the gallbladder and origin of the cystic duct. Contraction of the gallbladder against this obstruction produces pain in the right upper quadrant pain, which usually lasts 1-2 hours after eating a heavy meal.

Cholecystitis – obstruction of the biliary tree causing inflammation of the gallbladder, usually due to block- age of the cystic duct. Pain may be constant, unlike biliary colic, and there is often signs of inflammation, such as fever and raised white cell counts. The pain is classically felt in the right upper quadrant, radiating laterally beneath the right breast to the back, just below the inferior angle of the right scapula.

Choledocholithiasis – presence of gallstones within the common bile duct. Unlike biliary colic and chole- cystitis, this obstruction prevents bile from draining into the duodenum, resulting in a backlog of bile into the liver and ultimately jaundice. Patients may also complain of pale stools and dark urine.

Ascending cholangitis – as with choledocholithiasis, but with the presence of fevers (usually with rigors) and right upper quadrant pain (Charcot’s triad). Here the obstruction has promoted inflammation and infection of the biliary ducts.

Question 45

What level is the pancreas positioned on?

Answer 45

Transpyloric plane - L1

Question 46

Pancreas - infra or retro peritoneal?

Answer 46

With the exception of the tail of the pancreas, it is a retroperitoneal organ, located deep within the upper abdomen in the epigastrium and left hypochondrium regions.

Question 47

Anatomical structure of the pancreas

Answer 47

Head – the widest part of the pancreas. It lies within the C-shaped curve created by the duodenum and is connected to it by connective tissue.

Uncinate process – a projection arising from the lower part of the head and extending medially to lie beneath the body of the pancreas. It lies posterior to the superior mesenteric vessels.

Neck – located between the head and the body of the pancreas. It overlies the superior mesenteric vessels which form a groove in its posterior aspect.

Body – centrally located, crossing the midline of the human body to lie behind the stomach and to the left of the superior mesenteric vessels.

Tail – the left end of the pancreas that lies within close proximity to the hilum of the spleen. It is contained within the splenorenal ligament with the splenic vessels. This is the only part of the pancreas that is intraperitoneal.

Question 48

What does the pancreas do? What is it composed of?

Answer 48

The exocrine pancreas is classified as a lobulated, serous gland which produces digestive enzyme precursors. It is composed of approximately one million ‘berry-like’ clusters of cells called acini, connected by short intercalated ducts.

Question 49

Discuss duct system of pancreas

Answer 49

It is composed of approximately one million ‘berry-like’ clusters of cells called acini, connected by short intercalated ducts.

The intercalated ducts unite with those draining adjacent lobules and drain into a network of intralobular collecting ducts, which in turn drain into the main pancreatic duct.

The pancreatic duct runs the length of the pancreas and unites with the common bile duct, forming the hepatopancreatic ampulla of Vater. This structure then opens into the duodenum via the major duodenal papilla.

Question 50

What arteries is the pancreas supplied by?

Answer 50

The pancreas is supplied by the pancreatic branches of the splenic artery. The head is additionally supplied by the superior and inferior pancreaticoduodenal arteries which are branches of the gastroduodenal (from coeliac trunk) and superior mesenteric arteries, respectively.

Question 51

Venous drainage of pancreas

Answer 51

Venous drainage of the head of the pancreas is into the superior mesenteric branches of the hepatic portal vein. The pancreatic veins draining the rest of the pancreas do so via the splenic vein.

Question 52

Lymphatic drainage of pancreas?

Answer 52

The pancreas is drained by lymphatic vessels that follow the arterial supply. They empty into the pancreaticosplenal nodes and the pyloric nodes, which in turn drain into the superior mesenteric and coeliac lymph nodes.

Question 53

Examples of exocrine products from the pancreas

Endocrine example

Answer 53

trypsinogen, chymotrypsinogen, carboxypeptidase, lipase and amylase

The endocrine units of the pancreas are the islet of Langerhans, which produce insulin, glucagon and somato- statin. These products drain directly into the bloodstream.

Question 54

Innervation of pancreas?

Answer 54

. The pancreas is innervated by sympathetic fibres arising from the coeliac plexus, which control blood flow, and parasympathetic Vagal fibres, which stimulate pancreatic enzyme and insulin release.