Appendix Flashcards

Examine the vermiform appendix, including its cecal attachment, variable positions, mesoappendix, vascular supply, and clinical anatomy.

Card 1 of 28Question

What is the vermiform appendix?

A narrow, blind-ended tubular diverticulum arising from the cecum.

In This Section

1. What is the vermiform appendix?

A narrow, blind-ended tubular diverticulum arising from the cecum.

2. Where is the base of the appendix attached?

To the posteromedial wall of the cecum, approximately 2 cm below the ileocecal orifice.

3. In which abdominal region is the appendix usually located?

The right iliac fossa, within the right lower abdominal quadrant.

4. What is the approximate average length of the adult appendix?

About 9 cm, although its length varies considerably.

5. Which anatomical feature helps surgeons identify the base of the appendix?

The three taeniae coli of the cecum converge at its base.

6. What is the most common anatomical position of the appendiceal tip?

Retrocecal, behind the cecum.

7. What are the other recognized positions of the appendiceal tip?

Pelvic, subcecal, preileal, and postileal positions.

8. Which part of the appendix is relatively constant in position?

Its base at the cecum; the tip is considerably more variable.

9. How is the appendix classified in relation to the peritoneum?

It is an intraperitoneal organ, usually suspended by a mesoappendix.

10. What is the mesoappendix?

A peritoneal fold connecting the appendix to the mesentery of the terminal ileum.

11. Which artery primarily supplies the vermiform appendix?

The appendicular artery.

12. From which artery does the appendicular artery usually arise?

The ileocolic artery, usually through its inferior cecal branch.

13. Through which structure does the appendicular artery reach the appendix?

The mesoappendix.

14. Why is the appendicular artery clinically important as an end artery?

Its limited collateral supply makes the appendix vulnerable to ischemia when the artery is obstructed.

15. Into which major venous system does blood from the appendix eventually drain?

The hepatic portal system through the ileocolic and superior mesenteric veins.

16. Which lymph nodes primarily receive lymphatic drainage from the appendix?

Appendicular and ileocolic lymph nodes, followed by superior mesenteric nodes.

17. Which autonomic plexus provides sympathetic innervation to the appendix?

The superior mesenteric plexus.

18. Which cranial nerve provides parasympathetic innervation to the appendix?

The vagus nerve (cranial nerve X).

19. Which embryological division of the gastrointestinal tract gives rise to the appendix?

The midgut, as an outgrowth of the cecal diverticulum.

20. Which histological feature is particularly prominent in the appendiceal wall?

Abundant lymphoid follicles within the lamina propria and submucosa.

21. How does the appendix differ from the colon in its external longitudinal muscle arrangement?

Its outer longitudinal muscle forms a continuous layer rather than three distinct taeniae coli.

22. What is the established immunological role of appendiceal lymphoid tissue?

It contributes to gut-associated immune surveillance and mucosal immune responses.

23. What is McBurney's point?

A point approximately one-third of the distance from the right anterior superior iliac spine to the umbilicus.

24. Why is early appendicitis pain commonly felt around the umbilicus?

Visceral pain afferents from the midgut enter spinal cord segments around T10.

25. Why does appendicitis pain often become localized to the right lower quadrant?

Inflammation of the adjacent parietal peritoneum activates somatic pain afferents.

26. Which muscle may be irritated by an inflamed retrocecal appendix?

The psoas major muscle, producing a positive psoas sign.

27. Which muscle may be irritated by an inflamed pelvic appendix?

The obturator internus muscle, producing a positive obturator sign.

28. What is a common anatomical mechanism leading to acute appendicitis?

Obstruction of the appendiceal lumen, sometimes by a fecalith or lymphoid hyperplasia.