Mesocolon (Transverse, Sigmoid) Flashcards

Study the transverse and sigmoid mesocolon, including their attachments, vascular contents, peritoneal relationships, and surgical anatomy.

Card 1 of 30Question

What is a mesocolon?

A double-layered fold of peritoneum that attaches part of the colon to the posterior abdominal wall and transmits its vessels, nerves, and lymphatics.

In This Section

1. What is a mesocolon?

A double-layered fold of peritoneum that attaches part of the colon to the posterior abdominal wall and transmits its vessels, nerves, and lymphatics.

2. Which two major portions of the colon possess prominent mesocolons in typical adult anatomy?

The transverse colon and sigmoid colon.

3. What is the transverse mesocolon?

A peritoneal fold that suspends the transverse colon from the posterior abdominal wall.

4. Where does the root of the transverse mesocolon attach?

Along the anterior border of the pancreas and adjacent posterior abdominal wall.

5. Which part of the pancreas is closely related to the attachment of the transverse mesocolon?

The anterior border of the pancreatic body, with attachment extending across the pancreatic head region.

6. How does the transverse mesocolon divide the greater peritoneal sac?

Into supracolic and infracolic compartments.

7. Which organs are primarily located in the supracolic compartment?

The liver, stomach, and spleen.

8. Which intestinal structures occupy much of the infracolic compartment?

The jejunum and ileum, together with portions of the large intestine.

9. Which portion of the greater omentum is normally fused with the transverse mesocolon?

The ascending layers of the greater omentum.

10. Which ligament connects the greater curvature of the stomach to the transverse colon?

The gastrocolic ligament.

11. Which artery provides the principal blood supply to the transverse colon through its mesocolon?

The middle colic artery, usually a branch of the superior mesenteric artery.

12. Which artery commonly contributes to the blood supply of the distal transverse colon?

The left colic artery, a branch of the inferior mesenteric artery.

13. What is the marginal artery of the colon?

A continuous or variably connected arterial arcade along the mesenteric border of the colon, formed by colic arterial branches.

14. Which major vein receives most venous drainage from the proximal transverse colon?

The superior mesenteric vein through the middle colic vein.

15. Which lymph nodes receive lymph from the transverse colon through its mesocolon?

Epicolic, paracolic, and middle colic lymph nodes, with further drainage toward superior mesenteric nodes.

16. Which autonomic plexus supplies the proximal two-thirds of the transverse colon?

The superior mesenteric plexus.

17. What is the sigmoid mesocolon?

A double-layered peritoneal fold that attaches the sigmoid colon to the posterior pelvic and lower abdominal walls.

18. What is the typical shape of the root of the sigmoid mesocolon?

An inverted V-shaped attachment.

19. Where is the apex of the sigmoid mesocolon root usually located?

Near the bifurcation of the left common iliac artery, close to the pelvic brim.

20. Which ureter passes posterior to the root of the sigmoid mesocolon?

The left ureter.

21. Which major iliac vessels are related to the sigmoid mesocolon root?

The left common iliac vessels and their region of bifurcation.

22. What is the intersigmoid recess?

A small peritoneal recess that may occur behind the apex of the sigmoid mesocolon root.

23. Which arteries supply the sigmoid colon through its mesocolon?

The sigmoid arteries, usually branches of the inferior mesenteric artery.

24. Which vein primarily drains the sigmoid colon?

The inferior mesenteric vein through the sigmoid veins.

25. Which lymph nodes receive lymphatic drainage from the sigmoid colon?

Sigmoid and inferior mesenteric lymph nodes.

26. Which autonomic plexuses provide nerve fibers to the sigmoid colon?

The inferior mesenteric and hypogastric plexuses, including parasympathetic fibers from pelvic splanchnic nerves.

27. From which embryological structure do the transverse and sigmoid mesocolons develop?

The dorsal mesentery associated with their respective intestinal regions.

28. Why is the sigmoid colon particularly susceptible to volvulus?

Its relatively long, mobile mesocolon and potentially narrow mesenteric attachment allow twisting around its vascular pedicle.

29. Why must the left ureter be identified during sigmoid mesocolon dissection?

It lies posterior to the mesocolon root and is vulnerable to injury during colorectal surgery.

30. Why is the mesocolon important during oncological colon resection?

It contains the regional vessels and lymphatic drainage pathways that are considered during mesocolic excision.