1. Small Intestine & Pancreas
DEMO – IV
Small Intestine & Pancreas
Ali Jasim Alhashli
Year III – Unit V (GI & Renal Systems)

2. Station – 1 (Gross Anatomy of Small Intestine & Pancreas)
***Note: for anatomy of pancreas, watch the video***
Jejunum begins at the duodenojejunal junction & the ileum ends at the ileocecal junction.
The jejunum & ileum are 6-7 m long.
Note: Jejunum constitutes 2/5 of the length & the ileum 3/5 of the length.
The terminal ileum usually lies in the pelvis, from which it ascends to end in the medial aspect of the cecum.

3. Station – 1 (Gross Anatomy of Small Intestine & Pancreas)
The mesentery: fan-shaped fold of peritoneum, attaches the jejunum & the ileum to the posterior abdominal wall.
The root of the mesentery is 15 cm, directed obliquely, inferiorly & to the right.
It extends from the duodenojejunal junction on the left side of the L2 vertebra to the ileocolic junction & the right sacroiliac joint.
The root of the mesentery crosses:
-Ascending & horizontal parts
duodenum.
Abdominal aorta.
Inferior vena cava.
Right ureter.
Right testicular or ovarian vessels.
of the

4. Station – 1 (Gross Anatomy of Small Intestine & Pancreas)

5. Station – 1 (Gross Anatomy of Small Intestine & Pancreas)
Arterial supply
From SMA which runs between the layers of the mesentery & sends many branches to the jejunum & ileum:
•Loops = arterial arcades.
•Straight arteries = vasa recta.
Venous drainage
By SMV which joins the splenic vein behind the neck of the pancreas to form the hepatic portal vein.
Lymphatic drainage
Lacteals ---< lymphatic plexus in the walls of jejunum & ileum ---< lymphatic vessels between the layers of the mesentery ---< and then to 3 groups of lymph nodes:
•Juxta-intestinal.
•Mesenteric.
•Central superior.
Which will drain eventually into the superior mesenteric lymph nodes. Note: the terminal ileum drains to ileocolic lymph nodes.
Innervation
•Sympathetic stimulation reduces secretion & motility. Sympathetic fibers originate in the T8-T10 segments & synapse in the celiac & superior mesenteric ganglia.
•Parasympathetic fibers derive from the posterior vagal trunk & synapse in the myenteric & submucous plexus in the intestinal wall.

6. Station – 2 (Embryology of Midgut)
The midgut forms a U-shaped loop (midgut loop) that herniates through the primitive umbilical ring into the extraembryonic cavity (this is known as physiological umbilical herniation) at the 6th wk. this loop attaches to the umbilicus by the vetilline duct.
The midgut loop consists of a cranial limb (forming the jejunum and upper part of the ileum) and a caudal limb (forming the lower part of the ileum, cecum & appendix, ascending colon and proximal 2/3 of the transverse colon)
The midgut rotates a total 270 ( ) counterclockwise (عكس اتجاه عقارب الساعة) around an axis formed by the SMA.
Clinical consideration:
Omphalocele: occurs when the abdominal contents persist outside the body covered by peritoneum and aminion.
Ileal diverticulum (Meckel diverticulum): occurs when a remnant of the vetilline duct persist, thereby forming an outpouching of the ileum which may connect to the umbilicus via a fibrous cord or a fistula.
Non-rotation: occurs when the midgut loop rotates only 90 counterclockwise resulting in (left-sided colon).
Reversed rotation: occurs when the midgut loop rotates 180 clockwise instead of
counterclockwise. Therefore, the duodenum will be in front of the colon.
Mixed rotation: mixed positions of the structures.

7. Station – 2 (Embryology of Midgut)

8. Station – 3 (Imaging of The Small Intestine)
Giving a person Barium Sulfate in the form of barium meal will show us first the esophagus & if there is any obstruction in it caused by:
Achalasia.
Compression by an enlarged thyroid gland.
Hypertrophy of the left atrium of the heart.
When barium reaches the stomach, its shape and curvatures can be seen clearly. Once it reaches the small intestines, any of these abnormalities can be seen:
Erosions & ulcerations.
Perforations.
Polyps.
and even intestinal parasites.
Double-contrast barium radiograph: Barium Sulfate + Carbon Dioxide. It is
given rectally.

9. Station – 3 (Imaging of The Small Intestine)
Bird-beak seen in achalasia
Barium showing the stomach and the duodenum
Barium showing the stomach and the small intestine

10. Station – 3 (Imaging of The Small Intestine)
Double contrast barium of the small intestine
Double bubble sign seen in case of duodenal atresia caused by annular pancreas

11. Station – 3 (Imaging of The Small Intestine)
Esophagojejunostomy: no pancreatic enzymes will be released in the duodenum because it has been removed. Therefore, these enzymes must be gibe in synthetic form.
Overgrowth of the head of the pancreas might lead to compression of inferior vena cava which is located posterior to it. Therefore, resulting in lower limbs edema.
In acute pancreatitis, the pain will be referred to the back (dorsolumbar
region).
Carcinoma in the head of the pancreas will lead to the obstruction of the bile duct resulting in jaundice.
Overgrowth or carcinoma in the neck of the pancreas will lead to the compression of the portal vein at the level of L1 vertebra.

12. Station – 4 (Histology of The Small Intestine)

13. Station – 4 (Histology of The Small Intestine)

14. Station – 4 (Histology of The Small Intestine)

15. Station – 4 (Histology of The Small Intestine)

16. Station – 4 (Histology of The Small Intestine)

17. Station – 4 (Histology of The Small Intestine)

18. Station – 4 (Histology of The Small Intestine)

19. Station – 4 (Histology of The Small Intestine)

20. GOOD LUCK!