Large Intestine Anatomy

Question 1

Cecum

Answer 1

A small, inferior-projecting pouch at the very entrance to the colon. It’s guarded by the ileocecal sphincter

Question 2

Appendix

Answer 2

Small, inferior-hanging, twisting, coiled tube, attached to the cecum

Question 3

Ileocecal sphincter

Answer 3

The valve between the most distal part of the ileum and the cecum, guards the passage of chyme from the small to the large intestine

Question 4

Ascending colon

Answer 4

The most proximal segment of the colon. It ascends along the right wall of the abdomen poster enough to be retroperitoneal

Question 5

Transverse colon

Answer 5

The most superior portion of the colon, is distal to the ascending colon & proximal to the descending. It’s anterior enough to be peritoneal with a traditional serosa as the most superficial layer

Question 6

Descending colon

Answer 6

Running inferiorly along the left wall of the abdomen, distal to the transverse & proximal to the sigmoid colon. It’s posterior enough to be retroperitoneal

Question 7

Colic flexures

Answer 7

90-degree turns at the lateral aspects of the transverse colon, that mark transition from ascending to transverse, and transverse to descending

Question 8

Sigmoid colon

Answer 8

“S-shaped,” short segment of the colon, running anteriorly and medially. Distal to the descending colon & proximal to the rectum

Question 9

Rectum

Answer 9

The most distal portion of the colon. It runs inferiorly, distal to the sigmoid colon, and proximal to the anus. Its most distal portion is the anal canal

Question 10

Internal anal sphincter

Answer 10

Thickening of the muscularis near the distal end of the GI tract, guarding the anus. Just proximal to the external anal sphincter

Question 11

External anal sphincter

Answer 11

Just distal to the internal anal sphincter. Composed of skeletal muscle and is voluntarily relaxed to facilitate defecation

Question 12

Teniae coli

Answer 12

Thick bands of longitudinal muscle running lengthwise along the sections of the colon. Tonic (sustained) contraction bunches the colon into a distinct series of pouches called haustra

Question 13

Omental appendices

Answer 13

Small pouches of visceral peritoneum, filled with adipose tissue, hanging from the Teniae coli

Question 14

Haustra

Answer 14

Bunches segments of the colon that participate in haustral churning to move fecal matter distally along the colon