The hindgut and associated arteries. Liver, gallbladder and biliary tree.

Question 1

List the components of the hindgut.

Answer 1

Distal 1/3 of transverse colon, splenic flexure, descending colon, sigmoid colon, rectum.

Question 2

At what vertebral level is the inferior mesenteric artery given off?

Answer 2

L3

Question 3

Name the branches of the inferior mesenteric. What do they supply?

Answer 3

Left colic - descending colon, sigmoid (n=3-4) - descending and sigmoid colon.

Question 4

Which vessels contribute to the marginal artery?

Answer 4

From R->L: iliocolic, right colic, middle colic, left colic, sigmoid (multiple).

Question 5

What does the marginal artery supply.

Answer 5

The entire colon via the vasa recta.

Question 6

Why are gradual obstructions of the inferior mesenteric (via AAA) often asymptomatic?

Answer 6

Anastamoses between the right, middle and left colic enlarge the marginal artery to maintain a sufficient collateral blood supply.

Question 7

What is sigmoid volvulus?

Answer 7

Malrotation of the sigmoid colon about a focal point along the mesentery. May result in bowel obstruction.

Question 8

How do the peritoneal attachments of the rectum differ from those of the sigmoid colon?

Answer 8

The sigmoid colon is intraperitoneal whereas the rectum is retroperitoneal.

Question 9

What is the origin of the superior rectal artery and what does it supply?

Answer 9

Origin: terminal branch of the inferior mesenteric. Supplies the proximal part of the rectum.

Question 10

What is the origin of the middle rectal arteries? What do they supply?

Answer 10

Internal iliacs. Supply midpart of the rectum.

Question 11

What it the origin of the inferior rectal arteries? What do they supply?

Answer 11

Origin: internal pudendal. Supplies distal part of the rectum and anal canal.

Question 12

What is the definition of a portal vein?

Answer 12

A vein that collects blood from one part of the body and delivers it to another other than the heart.

Question 13

Individual veins draining the GI tract generally mirror the arterial supply. Where is not the case?

Answer 13

There is no coeliac vein and no gastroduodenal vein.

Question 14

To where do the veins of the foregut drain?

Answer 14

Either directly into the portal vein or one of its tributaries.

Question 15

Describe the venous drainage of the midgut.

Answer 15

Each smaller artery has a corresponding vein that drains into the superior mesenteric vein. The superior mesenteric vein drains into the splenic vein posterior to the neck of the pancreas to form the portal vein.

Question 16

Describe the venous drainage of the hindgut.

Answer 16

The hindgut tributary veins match the arteries. These veins drain into the inferior mesenteric. This then joins the splenic vein behind the body of the pancreas, just before the union of the splenic vein with the superior mesenteric vein.

Question 17

Into which vessel do the right and left gastric veins drain?

Answer 17

Portal vein.

Question 18

Into which vessel do the short gastric veins drain into?

Answer 18

Splenic vein.

Question 19

Into which vessel does the left gastroepiploic vein drain?

Answer 19

Splenic vein?

Question 20

Into which vein does the right gastroepiploic drain?

Answer 20

Superior mesenteric.

Question 21

Into which vein do the superior pancreaticoduodenal veins drain?

Answer 21

The superior mesenteric.

Question 22

Where do the oesophageal veins drain?

Answer 22

The aygos vein.

Question 23

List the sites of portosystemic anastamosis. What is their clinical significance.

Answer 23

Oesophageal veins (varices), rectal veins, paraumbilical with superficial epigastric (caput medusae), intrahepatic - portal vein with IVC (patent ductus venosus), retroperitoneal.

Question 24

What names are given to the clusters of lymph nodes that lie on the anterior surface of the abdominal aorta and what do they correspond to?

Answer 24

Coeliac nodes, superior mesenteric nodes and inferior mesenteric nodes. The lymphatic drainage generally corresponds to the arterial supply.

Question 25

Describe the lymphatic drainage of the rectum.

Answer 25

Lymph follows the superior rectal branch to the inferior mesenteric nodes AND the middle rectal artery to the internal iliac nodes.

Question 26

What is the cisterna chylli?

Answer 26

A dilated sac at the distal end (ie the beginning) of the thoracic duct (primary lymph vessel), lying on the anterior aspect of L1-2. It receives fatty chyle from the intestines and is the most common drainage site for most of the body’s lymphatics.

Question 27

Where would you find a myenteric plexus?

Answer 27

Muscularis externa.

Question 28

From which plexus do most of the autonomic fibres of the gut travel?

Answer 28

The coeliac plexus.

Question 29

From where do the parasympathetic fibres of the hindgut originate?

Answer 29

The inferior hypogastric plexus.

Question 30

What is the function of the vagus nerves with regards to the coeliac plexus?

Answer 30

Provide parasympathetic innervation to the foregut and midgut. Mainly responsible for peristalsis.

Question 31

What is the function of the splanchnic nerves with regards to the coeliac plexus?

Answer 31

he splanchnic nerves are paired visceral nerves , carrying fibers of the autonomic nervous system (visceral efferent fibers) as well as sensory fibers from the organs (visceral afferent fibers). The thoracic, lumbar and sacral splanchnic nerves all carry sympathetic fibres.

Question 32

Which splanchnic nerves carry parasympathetic fibres?

Answer 32

Pelvic.

Question 33

Where would pain from the foregut refer to?

Answer 33

Foregut structures are innervated by T5-T9 sympathetics and so refer pain to the corresponding dermatome – the epigastric region.

Question 34

Where would pain from the midgut refer to?

Answer 34

Midgut structures are innervated by T10&11 sympathetics and so refer pain to the corresponding dermatome – the umbilical region.

Question 35

Where would pain from the hindgut refer to?

Answer 35

Hindgut structures are innervated by T12-L1 sympathetics and so refer pain to the corresponding dermatome – the pubic region

Question 36

Why might inflammation of the gallbladder, liver or duodenum result in pain referring to the right shoulder?

Answer 36

Irritation of the diaphragm. The supraclavicular nerves have the same cervical origin as the diaphragm.

Question 37

What are the anterior relations of the liver?

Answer 37

Diaphragm, right and left costal margins, right and left pleura and lower margins of both lungs, xiphoid process, anterior abdominal wall.

Question 38

What are the posterior relations of the liver?

Answer 38

Diaphragm, right kidney, hepatic flexure of the colon, duodenum, gall bladder, inferior vena cava, oesophagus, fundus of stomach.

Question 39

What are the subphrenic recesses and what seperates them?

Answer 39

Superior extensions of the peritoneal cavity (greater sac) exist between diaphragm and the anterior/superior aspects of the diaphragmatic surface of the liver. They are seperated into right and left by the falciform ligament.

Question 40

What is the name of the space between the posterior surface of the liver and the right kidney?

Answer 40

The heptorenal recess.

Question 41

What is the bare area of the liver?

Answer 41

The only part of the liver that isn’t covered with visceral peritoneum. It is in direct contact with the diaphragm.

Question 42

What demarcates the bare area of the liver?

Answer 42

The reflection of the peritoneum from the diaphragm to it as the anterior and posterior coronary ligaments. These meet on the right to form the triangular ligament.

Question 43

What structure is found in the free edge of the falciform ligament?

Answer 43

Ligamentum teres - remnant of the umbilical vein.

Question 44

What is the porta hepatis?

Answer 44

Transverse fissure of the liver extending transversely across the under surface of the left portion of the right lobe of the liver, nearer its posterior surface than its anterior border. Carries the hepatic portal vein (entering), hepatic artery proper (entering) and common hepatic duct (leaving).

Question 45

Name the four anatomical lobes of the liver.

Answer 45

The left and right lobes are the largest lobes and are separated by the falciform ligament.
The small caudate lobe extends from the posterior side of the right lobe and wraps around the inferior vena cava.
The small quadrate lobe is inferior to the caudate lobe and extends from the posterior side of the right lobe and wraps around the gallbladder.

Question 46

What is the function of the gallbladder?

Answer 46

Holds and concentrates bile produced in the liver until it is needed for digesting fatty foods in the duodenum.

Question 47

Where does bile collect once it has been synthesised by liver cells?

Answer 47

Canaliculi

Question 48

What forms the common bile duct and where?

Answer 48

The cystic duct (from gallbladder) and hepatic duct (from liver). Formed in the free edge of the lesser omentum.

Question 49

What happens to the common bile duct once it leaves the free edge of the lesser omentum?

Answer 49

Descends posterior to the superior part of the duodenum and lies in a groove on the posterior surface of the head of the pancreas.

Question 50

Where does the pancreatic duct meet the common bile duct.

Answer 50

Hepatopancreatic ampulla of vater.

Question 51

What is the blood supply to the gallbladder? Where does it come from?

Answer 51

Cystic artery - comes off the R hepatic artery.

Question 52

Name the three main veins that drain the liver. How are they formed and what do they drain into?

Answer 52

Right, intermediate and left hepatic veins. Formed by the union of collecting veins. Open into the IVC.

Question 53

What proportion of lymph entering the thoracic duct is produced by the liver?

Answer 53

1/4 - 1/2

Question 54

Where is most of lymph formed in the liver?

Answer 54

Space of Disse

Question 55

Into what do the hepatic nodes drain?

Answer 55

Coeliac lymph nodes, which drain into the cisterna chyli.

Question 56

From where are the nerves of the liver derived?

Answer 56

The hepatic plexus - the largest derivative of the coeliac plexus. Accompanies the branches of the hepatic artery and portal vein to the liver.

Question 57

How is blood drained from neck of the gallbladder?

Answer 57

Via the cystic veins. Either enter the liver directly or drain through the hepatic portal vein to the liver after joining veins draining the hepatic ducts and proximal bile ducts.

Question 58

How is blood drained from the body and fundus of the gallbladder?

Answer 58

Veins pass directly into the visceral surface of the liver and drain into the hepatic sinusoids.

Question 59

Which node collects lymph from the liver?

Answer 59

Hepatic lymph nodes, often through the cystic lymph nodes.

Question 60

Describe the innervation of the gallbladder.

Answer 60

Nerves to gallbladder and cystic duct pass along cystic artery from the coeliac plexus (sympathetic and visceral afferent (pain)), the vagus (parasympathetic) and the right phrenic (somatic afferent fibres).