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TEST TAKING TIPS

Test Taking Tips

  • Know which nutrients are absorbed in which parts of the small intestine.

  • Know the various surgical options for strictures in Crohn disease. Try to lean more toward stricturoplasty in an attempt to preserve bowel. Know the various stricturoplasties.

EMBRYOLOGY

What does the cranial limb of the midgut loop develop into?

  • Distal duodenum, jejunum, and proximal ilium

What does the caudal limb of the midgut loop develop into?

  • Distal ilium and proximal two-thirds of the transverse colon

What structure joins the yolk sac to the juncture of the cranial and caudal limbs of the midgut loop?

  • The vitelline duct

What is a persistent vitelline duct otherwise known as?

  • Meckel diverticulum

How much does midgut loop rotate during normal physiologic herniation of bowel?

  • 270° counterclockwise rotation

ANATOMY

How long is the entire small intestine, from the pylorus to the cecum?

  • ~6 m (20 ft)

How long is the duodenum?

  • 26 cm (9.8 in.)

How long is the jejunum?

  • 2.5 m (8.2 ft)

How long is the ileum?

  • 3.5 m (11.5 ft)

What peritoneal fold supports the duodenojejunal angle, which marks where the duodenum ends and the jejunum begin?

  • Ligament of Treitz

FIGURE 19-1.

Blood supply and luminal surface of the small bowel. The arterial arcades of the small intestine increase in number from 1 or 2 in the proximal jejunum to 4 or 5 in the distal ileum, a finding that helps to distinguish proximal from distal bowel at operation. Plicae circulares are more prominent in the jejunum. (Reproduced with permission from Gerard M Doherty. CURRENT Diagnosis & Treatment: Surgery. 13th ed. http://www.accessmedicine.com. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.)

What are plicae circulares?

  • Circular folds of mucosa in the small bowel lumen (also known as valvulae conniventes)

Excluding the proximal duodenum, what artery supplies the entire blood supply of the small bowel?

  • Except for the proximal duodenum that is supplied by branches of the celiac axis, the supply comes entirely from the superior mesenteric artery (SMA).

Where is the parasympathetic innervation of the small bowel derived from?

  • Parasympathetic fibers are derived from the vagus, which traverse the celiac ganglion to supply the small bowel.

Where is the sympathetic innervation of the small bowel derived from?

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