Foregut, midgut, and hindgut

Question 1

The foregut gets its blood supply from which artery?

Which vertebral level is this artery?

Answer 1

Coeliac trunk – T12

Question 2

The midgut gets its blood supply from which artery?

Which vertebral level is this artery?

Answer 2

Superior mesenteric artery – L1

Question 3

The hindgut gets its blood supply from which artery?

Which vertebral level is this artery?

Answer 3

Inferior mesenteric artery – L3

Question 4

What are the boundaries of the foregut?

Answer 4

Lower oesophagus to the 2nd part of the duodenum / major duodenal papilla

Question 5

What are the boundaries of the midgut?

Answer 5

2nd part of the duodenum to 2/3rd of the way across the transverse colon

Question 6

What are the boundaries of the hindgut?

Answer 6

2/3rd of the way across the transverse colon to the upper anal canal

Question 7

The upper oesophageal sphincter is at which vertebral level?

Answer 7

C6/7

Question 8

Describe the types of muscle that make up the oesophagus, in terms of voluntary and automatic.

Answer 8

Skeletal muscle (voluntary) forms the upper 1/3rd and smooth muscle (automatic) forms the lower 2/3rd.

Question 9

An ultrasound probe can be inserted into the oesophagus to view which chamber of the heart?

Answer 9

Left atrium

Question 10

Describe how the vagus nerve travels into the abdomen with the oesophagus.

Answer 10

It wraps around the oesophagus as it splits into an anterior (left) vagal trunk and posterior (right) vagal trunk

Question 11

What is the vertebral level of the oesophageal hiatus?

Answer 11

T11-12

Question 12

Which structure forms the lower oesophageal sphincter?

Answer 12

Right crus of the diaphragm

Question 13

What are the 3 main branches of the coeliac trunk?

Answer 13

Common hepatic

Left gastric

Splenic

Question 14

Which 2 arteries does the common hepatic artery branch into?

Answer 14

Proper hepatic + gastroduodenal

Question 15

Which artery branches off the proper hepatic artery?

Answer 15

Right gastric

Question 16

Which 2 arteries does the gastroduodenal artery branch into?

Answer 16

Superior pancreaticoduodenal + right gastroepiploic

Question 17

The left gastric artery gives off which branches?

Answer 17

Oesophageal branches

Question 18

The splenic artery branches into which 2 structures?

Answer 18

Short gastric arteries + left gastroepiploic

Question 19

The fundus of the stomach is supplied by which arteries?

Answer 19

Short gastric arteries

Question 20

The gastroduodenal artery passes directly behind what?

What does this make the gastroduodenal artery susceptible to damage from?

Answer 20

1st part of the duodenum – a duodenal ulcer which erodes through the wall and into the artery

Question 21

Describe the duodenum in terms of its peritoneal covering.

Answer 21

Retroperitoneal except for the 1st part

Question 22

The duodenum spans which vertebral levels?

Answer 22

L1 – L3

Question 23

Which structure holds up the duodeno-jejunal flexure?

Answer 23

Ligament of Treitz

Question 24

The ligament of Treitz can be used as a marker to distinguish between what?

Answer 24

Upper and lower GI bleeds

Question 25

Describe the blood supply to the duodenum.

Answer 25

Anterior and posterior superior pancreaticoduodenal arteries from the gastroduodenal artery Anterior and posterior inferior pancreaticoduodenal arteries from the SMA.

Question 26

If an aneurysm in the SMA was compressing the duodenum, which surgical procedure could be carried out to mobilise and reposition the duodenum? What is this procedure known as?

Answer 26

Cut the ligament of Treitz Strong’s procedure

Question 27

Describe if each omentum develops from the dorsal or ventral mesentery.

Answer 27

Greater omentum – dorsal mesentery Lesser omentum – ventral mesentery

Question 28

What 3 things are found in the free lower edge of the lesser omentum, within the hepatoduodenal ligament?

Answer 28

Common bile duct Hepatic artery Portal vein

Question 29

From which artery does the appendicular artery branch off?

Answer 29

Ileocolic artery

Question 30

Which artery connects many of the distal portions of the SMA arteries?

Answer 30

Marginal artery

Question 31

Describe the jejunum in terms of arterial arcades, vasa recta length, lumen size, and wall thickness.

Answer 31

Few arterial arcades Long vasa recta Wide lumen Thick wall

Question 32

Describe the ileum in terms of arterial arcades, vasa recta length, lumen size, and wall thickness.

Answer 32

Lots of arterial arcades Short vasa recta Smaller lumen Thinner wall

Question 33

Describe the peritoneal covering of the caecum.

Answer 33

Mostly intraperitoneal

Question 34

Describe the peritoneal covering of the appendix.

Answer 34

Intraperitoneal

Question 35

Describe the pain felt with appendicitis and why this happens.

Answer 35

Pain at the umbilicus which then moves to the right iliac fossa. This is because early visceral pain is felt at the umbilicus since the appendix is a midgut structure, but later stage somatic pain is felt as the appendix inflames nearby parietal peritoneum in the right iliac fossa – McBurney’s point.

Question 36

What is intussusception?

Answer 36

Proximal segment of bowel telescopes into an adjacent distal segment, dragging the mesentery with it

Question 37

In which area of the bowel does intussusception typically occur?

Answer 37

Ileocaecal junction

Question 38

What causes the formation of a Meckel’s diverticulum?

Answer 38

The vitelline duct fails to disappear and a remnant (diverticulum) of tissue remains attached to the ileum

Question 39

Which section of the gut tube is prone to twisting on itself, and what is this pathology called?

Answer 39

Sigmoid colon – volvulus

Question 40

What sign can be seen on imaging that suggests a colorectal adenocarcinoma?

Answer 40

Apple core sign

Question 41

How can infections spread from under the diaphragm to the pelvic cavity and vice versa?

Answer 41

Via the paracolic gutters

Question 42

What is the deepest and most superior part of the right paracolic gutter?

Answer 42

Hepatorenal recess

Question 43

What are the 3 main branches of the IMA?

Answer 43

Left colic Sigmoidal Superior rectal

Question 44

What is a watershed area?

Answer 44

A tissue that receives dual blood supply from the most distal branches of arteries

Question 45

Where is the watershed area in the GI tract? What name is given to this area and what is it at risk of if something were to compromise either or both of its blood supplies?

Answer 45

The junction between the midgut and hindgut – 2/3rd way across transverse colon – known as Griffith’s point, and is at risk of ischaemia if either blood supply is compromised.

Question 46

Describe lymphatic drainage from the GI tract.

Answer 46

Cisterna chyli - thoracic duct - left supraclavicular nodes - left subclavian vein

Question 47

Which bony landmark signifies the transition from rectum to anal canal?

Answer 47

Tip of the coccyx

Question 48

Which nerve innervates the external anal sphincter?

Answer 48

Pudendal nerve

Question 49

In the anal canal, what does the pectinate line signify?

Answer 49

A change in nervous innervation

Question 50

What is the innervation of the anal canal below the pectinate line?

Answer 50

Inferior rectal nerve

Question 51

Describe the blood supply to the rectum.

Answer 51

Superior rectal artery from the IMA Middle and inferior rectal arteries from the internal iliac artery

Question 52

What are porto-systemic anastomoses?

Answer 52

Connections between veins that drain to the liver (via the portal vein) and veins that drain to the heart (via the IVC)

Question 53

The inferior mesenteric vein drains into where?

Answer 53

Splenic vein

Question 54

Give the 3 key areas of porto-systemic anastomoses.

Answer 54

Lower oesophagus Upper anal canal Umbilical region on anterior abdominal wall

Question 55

If the liver became cirrhotic, given that the upper anal canal is an area of porto-systemic anastomoses, what pathology could this result in?

Answer 55

Anorectal varices

Question 56

What is the commonly reported position of haemorrhoids?

Answer 56

3, 7 & 11 o’clock

Question 57

Why is a tumour in the descending colon likely to present with symptoms sooner than a tumour in the ascending colon?

Answer 57

Stool in the descending colon is firmer and the lumen is narrower

Question 58

The portal vein is formed by the union of what?

Answer 58

SMV + splenic vein

Question 59

If a stomach ulcer erodes posteriorly, which organ and major artery is at risk?

Answer 59

Pancreas Splenic artery