Small intestine

Question 1

Compare the mobility of the small intestine with the large intestine

Answer 1

Small intestine is mobile except the duodenum

Large intestine is mobile except the ascending and descending colon

Question 2

Compare the lumen diameter of the small intestine with the large intestine

Answer 2

Lumen of the large intestine is much larger

Question 3

Compare the longitudinal muscle of the small intestine with the large intestine

Answer 3

The small intestine has continuous longitudinal muscle

The large intestine has 3 bands of longitudinal muscle called teniae coli

Question 4

Compare the presence of fatty tags in the small intestine with the large intestine

Answer 4

Small intestine has none

Large intestine has fatty tags called epiploic appendices

Question 5

Compare the wall of the small intestine with the large intestine

Answer 5

Small intestine wall is smooth

Large intestine wall is sacculated forming haustra

Question 6

Compare the mucous membrane of the small intestine with the large intestine

Answer 6

Small intestine has permanent folds in its mucous membrane called plicae circulares
Large intestine doesn’t have plicae circulares

Question 7

Compare the lymphoid tissue in the small intestine with the large intestine

Answer 7

Small intestine has peyer’s patches

Large intestine has no lymphoid tissue

Question 8

Where does the small intestine run from and to

Answer 8

From the pylorus so the stomach to the ileoceacal junction

Question 9

Parts of the small intestine

Answer 9

Duodenum
Jejunum
Ileum

Question 10

How long is the duodenum

Answer 10

Breadth of 12 fingers (25cm)

Question 11

Where does the duodenum run from and to

Answer 11

From the pylorus of the stomach to the duodenojejunal flexure

Question 12

Shape of the duodenum

Answer 12

C shape that wraps around the head of pancreas

Question 13

Describe the duodenojejunal flexure

Answer 13

Acute angle

2-3cm to the left of the midline at the level of the L2 vertebra

Question 14

What are the parts of the duodenum

Answer 14

Superior
Descending
Inferior
Ascending

Question 15

Where is the duodenal cap/ampulla

Answer 15

First 2cm of the superior duodenum

Question 16

Mobility of the duodenum

Answer 16

Immobile except the ampulla which has a mesentery

Question 17

Length of the superior duodenum

Answer 17

5cm

Question 18

Where is the superior duodenum in relation to the vertebra

Answer 18

Anterolateral to L1

Question 19

What is the most common site for duodenal ulcers and why

Answer 19

Ampulla as its immediately distal to the pylorus of the stomach

Question 20

What is attached superiorly and inferiorly to the superior duodenum

Answer 20

Superiorly - attached to the liver by the hepatoduodenal ligament
Inferiorly - attached to the greater omentum

Question 21

Length of the descending duodenum

Answer 21

7-10cm

Question 22

Where is the descending duodenum in relation to the vertebrae

Answer 22

Right of L1-3

Question 23

What lies anterior and posterior to the descending duodenum

Answer 23

Anterior - transverse colon

Posterior - right kidney

Question 24

What internal feature of the descending duodenum distinguishes it from the other parts

Answer 24

Major duodenal papilla

Question 25

What does the major duodenal papilla allow entry of

Answer 25

Bile and pancreatic secretions

Question 26

Where does the transverse mesocolon form

Answer 26

Middle third of the descending duodenum

Question 27

Length of the inferior duodenum

Answer 27

6-8cm

Question 28

Where is the inferior duodenum in relation to the vertebrae

Answer 28

Crosses the L3 vertebra (right to left)

Question 29

What lies posterior to the inferior duodenum

Answer 29

Aorta IVC L3 vertebra

Question 30

What lies anterior to the inferior duodenum

Answer 30

SMA SMV Root of mesentery of the small intestine

Question 31

Length of the ascending duodenum

Answer 31

5cm

Question 32

Where is the ascending duodenum in relation to the vertebrae

Answer 32

From left of L3 vertebra to the superior margin of L2 vertebra

Question 33

Course of the ascending duodenum

Answer 33

Ascends along the left side of the aorta to reach the inferior border of the body of pancreas It then curves to join the Jejunum at the duodenojejunal flexure

Question 34

What supports the duodenojejunal flexure

Answer 34

Suspensory muscle of the duodenum (ligament of Treitz)

Question 35

What does contraction of the suspensory muscle of the duodenum do

Answer 35

Widens the angle of the duodenojejunal flexure which increases movement of the intestinal contents into the Jejunum

Question 36

What's a duodenal ulcer

Answer 36

Erosion of the duodenal mucosa

Question 37

Common causes of duodenal ulcers

Answer 37

Infections by helicobacter pylori | Chronic NSAID use

Question 38

Complications of duodenal ulcers

Answer 38

Can perforate duodenal wall, leading to: Peritonitis Erosion of gastroduodenal artery causing severe haemorrhage

Question 39

Length of the Jejunum and ileum

Answer 39

6-7m overall Jejunum makes up 2/5 Ileum makes up 3/5

Question 40

What does the mesentery of the small intestine connect

Answer 40

Intraperitoneal section of the small intestine to the posterior abdominal wall

Question 41

What's between the layers of the mesentery of the small intestine

Answer 41

Superior mesenteric vessels Lymph nodes Fat Autonomic nerves

Question 42

What does the root of mesentery of the small intestine cross

Answer 42

``` Ascending and inferior duodenum Abdominal aorta IVC Right ureter Right psoas major Right testicular/ovarian vessels ```

Question 43

Compare the colour of the Jejunum and ileum

Answer 43

Jejunum is deep red | Ileum is pale pink

Question 44

Compare the diameter of the Jejunum and ileum

Answer 44

Jejunum is 2-4cm | Ileum is 2-3cm

Question 45

Compare the wall of the Jejunum and ileum

Answer 45

Wall of Jejunum is thick and heavy | Wall of ileum is thin and light

Question 46

Compare the vascularity of the Jejunum and ileum

Answer 46

Jejunum is more vascular than the ileum Vasa recta are longer in the jejunum Jejunum has fewer arcades with larger loops

Question 47

Compare the fat in the mesentery of the Jejunum and ileum

Answer 47

Ileum has more

Question 48

Compare the plicae circulares of the Jejunum and ileum

Answer 48

In the Jejunum they are large, tall and closely packed In the ileum they are low and sparse They are absent in the distal ileum

Question 49

Compare the number of peyer's patches in the Jejunum and ileum

Answer 49

Ileum has more

Question 50

Link embryological origins of the small intestine to their blood supply

Answer 50

Duodenum proximal to the bile duct is derived from the foregut therefore it's supplied by the coeliac trunk Duodenum distal to the bile duct, Jejunum and ileum are derived from the midgut therefore they're supplied by the superior mesenteric vessels

Question 51

Arterial supply of the duodenum proximal to the bile duct

Answer 51

Coeliac trunk -> gastroduodenal -> superior pancreaticoduodenal artery

Question 52

Arterial supply of the duodenum distal to the bile duct

Answer 52

Abdominal aorta -> superior mesenteric artery -> inferior pancreaticoduodenal artery

Question 53

Venous drainage of the duodenum

Answer 53

Pancreaticoduodenal veins follow the arteries into the hepatic portal vein, either: Directly Indirectly - superior mesenteric vein and splenic vein

Question 54

Arterial supply of the Jejunum

Answer 54

Abdominal aorta -> SMA -> jejunal artery

Question 55

Arterial supply of the ileum

Answer 55

Abdominal aorta -> SMA -> ileal artery

Question 56

Where does the SMA arise

Answer 56

Level of the L1 vertebra about 1cm inferior to the coeliac trunk

Question 57

What do the jejunal and ileal arteries form

Answer 57

Arterial arcades which give rise to vasa recta

Question 58

Venous drainage of the Jejunum and ilium

Answer 58

Superior mesenteric vein