Small Intestine - Anatomy

Question 1

Where does the SI extend to and from?

Answer 1

From the pylorus of the stomach to the ileocaecal junction where it meets the LI at the ileocaecal valve

Question 2

What are the 3 parts of the SI?

Answer 2

Duodenum, jejunum, ileum

Question 3

Where does the duodenum run to and from?

Answer 3

From the pylorus of the stomach to the duodenojejunal junction.

Question 4

Describe the first section (superior) of the duodenum

Answer 4

It ascends upwards from the pylorus of the stomach, and is connected to the liver by the hepatoduodenal ligament

The first part of the duodenum is intraperitoneal, with the remained being retroperitoneal (only covered anteriorly)

Question 5

Describe the second section (descending) of the duodenum

Answer 5

Curves inferiorly around the head of the pancreas. It lies posteriorly to the transverse colon, and anterior to the right kidney.

Question 6

What is the descending duodenum marked by internally?

Answer 6

The major duodenal papilla

Question 7

What is the major duodenal papilla?

Answer 7

The opening at which bile and pancreatic secretions to enter from the ampulla of Vater (hepatopancreatic ampulla).

Question 8

Describe the third section (inferior) of the duodenum?

Answer 8

Travels laterally to the left, crossing over the inferior vena cava and aorta. It is located inferiorly to the pancreas, and posteriorly to the superior mesenteric artery and vein

Question 9

Describe the fourth section (ascending) of the duodenum?

Answer 9

After the duodenum crosses the aorta, it ascends and curves anteriorly to join the jejunum

Question 10

Where does the duodenum meet the jejunum?

Answer 10

At the duodenojejunal flexure (sharp turn)

Question 11

What is located at the duodenojejunal flexure?

Answer 11

The suspensory ligament of the duodenum / ligament of treitz

Piece of peritoneum (causing duodenum to ascend slightly)

Question 12

What is a duodenal ulcer?

Answer 12

The erosion of the mucosa in the duodenum. It may also be described as a peptic ulcer (although this term can also be used to refer to ulcerations in the stomach)

Question 13

Where are duodenal ulcers likely to occur?

Answer 13

In the superior portion of the duodenum.

Question 14

What can the duodenum be divided into?

Answer 14

4 parts:

1. Superior
2. Descending
3. Inferior
4. Ascending

Together these parts form a ‘C’ shape, and which wraps around the head of the pancreas.

Question 15

How are the jejunum and ileum attached to the posterior abdominal wall?

Answer 15

A mesentery

Question 16

Where does the ileum end?

Answer 16

At the ileocaecal junction.

Question 17

What is function of ileocaecal valve?

Answer 17

It can prevent reflux of material back into the ileum

Question 18

Where is the jejunum/ileum located?

Answer 18

Upper left quadrant / lower right quadrant

Question 19

Describe the wall of the jejunum/ileum

Answer 19

Thick / thin

Question 20

Describe the vasa recta (straight arteries) of the jejunum/ileum

Answer 20

Longer / shorter

Question 21

Describe the arcades (arterial loops) of the jejunum/ileum

Answer 21

Less arcades / more arcades

Question 22

Describe the colour of the jejunum/ileum

Answer 22

Red / pink

Question 23

What is the section of the duodenum proximal to the major duodenal papilla supplied by?

Answer 23

The gastroduodenal artery (branch of the coeliac trunk).

Question 24

What is the section of the duodenum distal to the major duodenal papilla supplied by?

Answer 24

Supplied by the inferior pancreaticoduodenal artery (branch of superior mesenteric artery).

Question 25

Why is the transition from proximal to distal to the major duodenal papilla important?

Answer 25

It marks the change from the embryological foregut to midgut

Question 26

Where do the veins of the duodenum drain into?

Answer 26

The hepatic portal vein

Question 27

Where is lymphatic drainage of the duodenum to?

Answer 27

The pancreatoduodenal and superior mesenteric nodes.

Question 28

Where is the arterial supply to the jejunum and ileum from?

Answer 28

The superior mesenteric artery.

Question 29

Where does the SMA arise from the aorta?

Answer 29

At level L1, immediately inferior to the coeliac trunk

Question 30

What does the SMA branch into?

Answer 30

It moves in between layers of mesentery, splitting into approximately 20 branches. These branches anastomose to form loops, called arcades.

Question 31

What arises from the arcades?

Answer 31

Long and straight arteries arise, called vasa recta.

Question 32

What is venous drainage of the jejunum and ileum via?

Answer 32

The superior mesenteric vein

Question 33

What does the SMV unite with?

Answer 33

The splenic vein at the neck of the pancreas to form the hepatic portal vein.

Question 34

Where is lymphatic drainage of the jejunum and ileum into?

Answer 34

The superior mesenteric nodes.