Large Intestine Flashcards

Explore the large intestine's regional anatomy, distinctive wall features, vascular supply, innervation, and role in fecal formation.

Card 1 of 30Question

What are the major anatomical divisions of the large intestine?

The cecum, appendix, colon, rectum, and anal canal.

In This Section

1. What are the major anatomical divisions of the large intestine?

The cecum, appendix, colon, rectum, and anal canal.

2. Where does the large intestine begin?

At the cecum in the right iliac fossa, where the terminal ileum enters through the ileocecal orifice.

3. What is the approximate length of the adult large intestine?

Approximately 1.5 meters, although length varies considerably.

4. What are the four anatomical segments of the colon?

Ascending, transverse, descending, and sigmoid colon.

5. What are the three characteristic external features of the colon?

Taeniae coli, haustra, and epiploic appendages.

6. What are the taeniae coli?

Three longitudinal bands of smooth muscle formed by thickening of the outer longitudinal layer of the colonic muscularis externa.

7. What are the three named taeniae coli?

Taenia libera, taenia mesocolica, and taenia omentalis.

8. What are the haustra of the colon?

Sacculations of the colonic wall formed partly by the shorter length of the taeniae coli relative to the colon.

9. What are epiploic appendages?

Small, fat-filled peritoneal projections attached to the external surface of the colon.

10. Where is the vermiform appendix attached to the cecum?

At the posteromedial cecal wall, approximately 2 cm inferior to the ileocecal orifice.

11. Which anatomical feature helps locate the base of the vermiform appendix during surgery?

The three taeniae coli converge at the appendiceal base.

12. What is the anatomical function of the ileocecal valve?

It helps regulate ileal emptying into the cecum and limits reflux of colonic contents into the ileum.

13. Which flexure connects the ascending colon to the transverse colon?

The right colic flexure, also called the hepatic flexure.

14. Which flexure connects the transverse colon to the descending colon?

The left colic flexure, also called the splenic flexure.

15. Which segments of the colon are usually secondarily retroperitoneal?

The ascending and descending colon.

16. Which segments of the colon are typically suspended by mesocolon?

The transverse and sigmoid colon.

17. At approximately which vertebral level does the sigmoid colon become continuous with the rectum?

At the level of S3.

18. How does the rectum differ externally from the colon?

It lacks distinct taeniae coli, haustra, and epiploic appendages.

19. What are the four principal histological layers of the large intestinal wall?

Mucosa, submucosa, muscularis externa, and serosa or adventitia.

20. Which mucosal glands are abundant in the colon?

Straight tubular intestinal glands, also called crypts of Lieberkuhn, containing numerous goblet cells.

21. Which major absorptive structures of the small intestine are absent from the colonic mucosa?

Intestinal villi.

22. What are the principal physiological functions of the large intestine?

Absorption of water and electrolytes, microbial fermentation, and formation, storage, and elimination of feces.

23. Which artery primarily supplies the cecum, ascending colon, and proximal transverse colon?

The superior mesenteric artery through its ileocolic, right colic, and middle colic branches.

24. Which artery primarily supplies the descending colon, sigmoid colon, and upper rectum?

The inferior mesenteric artery through its left colic, sigmoid, and superior rectal branches.

25. What is the marginal artery of the colon?

A longitudinal arterial arcade near the mesenteric border that connects branches of the superior and inferior mesenteric arteries.

26. Through which venous system does most blood from the colon drain toward the liver?

The hepatic portal venous system via the superior and inferior mesenteric veins.

27. Which lymph nodes receive lymph from the colon before it reaches the intestinal lymphatic trunks?

Epicolic, paracolic, intermediate, and principal mesenteric lymph nodes.

28. Which nerves provide parasympathetic innervation to the large intestine?

The vagus nerve supplies the proximal colon, while pelvic splanchnic nerves from S2 to S4 supply the distal colon and rectum.

29. Through which major autonomic plexuses does sympathetic innervation reach the colon?

The superior and inferior mesenteric plexuses, with additional hypogastric plexus connections to the distal bowel.

30. Which two regions of the colon are important vascular watershed areas?

The splenic flexure near Griffith's point and the rectosigmoid junction near Sudeck's point.