Rectum

Question 1

How long is the rectum

Answer 1

15cm

Question 2

What vertebral level does the rectosigmoid junction occur at

Answer 2

S3

Question 3

Describe peritoneal covering of the rectum

Answer 3

First third - peritoneum over anterior and lateral surfaces
Middle third - peritoneum over anterior surface
Last third - subperitoneal

Question 4

What happens to smooth muscle at the rectosigmoid junction

Answer 4

Teniae coli of the sigmoid colon spread to form a continuous outer longitudinal layer of smooth muscle

Question 5

What are the major flexures of the rectum

Answer 5

Sacral

Anorectal

Question 6

What is the sacral flexure

Answer 6

Anteroposterior curve following the curve of the sacrum and coccyx, therefore it is concave anteriorly

Question 7

What is the anorectal flexure

Answer 7

Anteroposterior curve that is concave posteriorly

Question 8

What forms the anorectal flexure

Answer 8

Tone of the puborectalis muscle

Question 9

Function of the anorectal flexure

Answer 9

Contributes significantly to faecal continence (ability to control bowel movements)

Question 10

What are the lateral flexures of the rectum

Answer 10

Superior
Intermediate
Inferior

Question 11

What forms the lateral flexures

Answer 11

Transverse folds of the internal rectal wall

Question 12

What is the distal segment of the rectum

Answer 12

Ampulla

Question 13

Function of the ampulla of the rectum

Answer 13

It relaxes to accumulate and temporarily store faeces until defecation occurs

Question 14

What’s directly anterior to the rectum in males and females

Answer 14

Males - rectovesical pouch

Females - rectouterine pouch

Question 15

Link embryological origins to the blood supply of the rectum

Answer 15

The proximal rectum is derived from the hindgut and so its blood supply is via the inferior mesenteric artery
The distal rectum receives its blood supply from branches off the internal iliac arteries

Question 16

Arterial supply of the proximal rectum

Answer 16

Aorta -> IMA -> right and left superior rectal arteries

Question 17

Arterial supply of the distal rectum

Answer 17

Aorta -> common iliac -> right and left internal iliac -> right and left middle rectal arteries
Aorta -> common iliac -> right and left internal iliac -> inferior pudendal -> right and left inferior rectal arteries

Question 18

Venous drainage of the rectum

Answer 18

Superior, middle and inferior rectal veins

Question 19

What does the superior rectal vein drain into

Answer 19

IMV, splenic vein then the hepatic portal vein

Question 20

What do the middle and inferior rectal veins drain into

Answer 20

Systemic venous system

Question 21

Site of the portocaval anastomosis (where do the portal and systemic venous systems anastomose)
What is the significance of this

Answer 21

Wall of the anal canal

Clinically important in varices (portal hypertension)

Question 22

Innervation of the rectum

Answer 22

Sympathetic - lumbar splanchnic nerves and the superior and inferior hypogastric plexuses
Parasympathetic (S2-4) - pelvic splanchnic nerves and inferior hypogastric plexus

Question 23

What does lymph from the rectum drain into

Answer 23

Pararectal lymph nodes

Additionally, lymph from the distal rectum drains directly into the internal iliac lymph nodes

Question 24

What do pararectal lymph nodes empty into

Answer 24

Inferior mesenteric nodes

Question 25

What can be palpated digitally via the rectum

Answer 25

Prostate 
Seminal vesicles 
Cervix
Sacrum 
Coccyx