Anatomy - Colorectal

Question 1

How long is the large intestine in length and diameter?

Answer 1

1.5cm in length and 6cm in diameter

Question 2

What are the 4 principle regions?

Answer 2

Caecum
Colon
Rectum
Anal canal

Question 3

What is the caecum?

Answer 3

First part of the large intestine
Lies behind the right iliac fossa
6cm long and 7.5cm wide

Question 4

What are the 4 parts of the colon?

Answer 4

The ascending colon
The transverse colon
The descending colon
The sigmoid colon

Question 5

Where is the rectum located?

Answer 5

At the lower end of the sigmoid colon at the level of the third sacral vertebra

Question 6

How long is the anal canal in length?

Answer 6

4cm

Question 7

What are the 4 layers of the GI tract from the inside out?

Answer 7

Mucosa
Submucosa
Muscularis
Serosa

Question 8

What are the 3 layers of the mucosa?

Answer 8

Epithelium
Lamina Propria
Muscularis Mucosae

Question 9

What are the 2 muscle layers of the muscularis?

Answer 9

Circular muscle
Longitundial muscle

Question 10

What is the mesocolon?

Answer 10

Peritoneum that attaches large intestine to the posterior abdominal wall

Question 11

What is the ileacaecal sphincter (valve)?

Answer 11

Fold of the membrane that acts a valve, regulating the passage of materials from ilium to large intestine

Question 12

What is the vermiform appendix?

Answer 12

Lies behind caecum and ascending colon
About 7.5cm long
Contains lymphoid tissue

Question 13

The caecum, appendix and ascending colon are all supplied with arterial blood branches from which artery?

Answer 13

Superior mesenteric artery

Question 14

The left 1/3rd of the transerve colon, the descending colon, the sigmoid colon, the rectum and the upper part of the anal canal are all supplied with arterial blood from which artery?

Answer 14

Inferior mesenteric artery

Question 15

Where is the veins from the large intestine drain into?

Answer 15

The superior and inferior mesenteric veins which in turn drain into the portal circulation

Question 16

What supplies the intestines in terms of nerves?

Answer 16

The coeliac plexus of the sympathetic nervous system - responsible for decreasing motility of the intestine

Question 17

What supplies the large intestine in terms of nerves?

Answer 17

The vagus nerve of the parasympathetic nervous system - causing increased motor activity and relaxation of sphincters

Question 18

What leads to the relaxation of anal sphincters?

Answer 18

Stimulation of sensory nerves in anal wall by distension

Question 19

Where do the vessels drain (lymphatic) in the colon?

Answer 19

Vessels drain into the inferior and superior mesenteric lymph glands and lymph vessels