L10 Small Intestine and Mesentery

Question 1

Shortest and widest segment of the small intestine?

Answer 1

Duodenum (25cm)

C-shaped around pancreas and Retroperitoneal

Question 2

Thick, heavy highly vascular section of small intestine?

Answer 2

Jejunum (2.5 Meters)

Question 3

Thin and light less vascular section of the small intestine?

Answer 3

Ileum (3.5 Meters)
Encroaching fat
MALT
Peyers Patches

Question 4

Wall structure of small intestine

Answer 4

Question 5

Relationships of Superior Duodenum (D?)

Answer 5

Superior Duodenum (D1)

1st 2cm has mesentery: duodenal cap: retroperitoneal thereafter

Anterolateral to L1 body, gastroduodenal artery, bile duct, portal vein

Lies posterior to gallbladder & quadrate lobe of liver.

Question 6

Relationships of Descending Duodenum (D?)

Answer 6

Descending Duodenum (D2)

Bile duct, pancreaticoduodenal vessels enter @ right side of L2 & L3

Right of IVC and bile duct, anterior to hilum of right kidney, psoas major

Question 7

Relationships of Horizontal Duodenum (D?)

Answer 7

Horizontal Duodenum (D3)

Posterior to SMA

@L3 Crosses IVC & aorta (origin of inferior mesenteric artery , right gonadal vessels & ureter)

Question 8

Relationships of Ascending Duodenum (D?)

Answer 8

Ascending Duodenum (D4)

left of midline and aorta

right of inferior mesenteric vein & left ureter

Posterior to coils of jejunum

Question 9

What creates the acute angle at the Duodeno-Jejunal Junction?

Answer 9

Suspensory Ligament of Treitz:
Skeletal muscle from diaphragm
Fibromuscular bands from duodenum

Question 10

Role of the Mesentery Proper?

Answer 10

Question 11

Duodenum Arterial Supply?

Answer 11

D1 & D2:
Coeliac trunk via gastroduodenal artery and superior pancreaticoduodenal artery

D3 & D4:
Superior mesenteric artery (SMA) via inferior pancreaticoduodenal artery

Question 12

Jejunoileum Arterial Supply?

Answer 12

Superior mesenteric artery:
-15-18 branches running within mesentery
-Formation of arcades
-Emergence of straight arteries

Question 13

Venous drainage of gut ,spleen and pancreas?

Answer 13

Portal Venous System

Blood passes through liver sinusoids before draining to IVC via hepatic veins

Question 14

Sympathetic Innervation of the Small Intestine

Answer 14

↓secretion ↓ motility, ↓ blood flow

T8-10 to SMA periarterial nerve plexus

Sympathetic trunks, greater, lesser and least splanchnic nerves

Question 15

Parasympathetic Innervation of the Small Intestine

Answer 15

Posterior vagal trunk
Myenteric & submucosal plexuses