Rectum (dave's notes)

Question 1

Describe the curves of the rectum

Answer 1

This could be added to from Prof Bissett’s lecture
Posteriorly, the rectum follows the posterior concavity of the sacrum, but also has three curves; the upper and lower to the right. Must know concave/convex what direction

Question 2

What are the folds within the rectum called and what are they made of? What is their function?

Answer 2

The folds of Houston are made from the inner circular muscle layer of the wall. They help to separate flatus.

Question 3

What is the lowest part of the rectum called?

Answer 3

The lowest, slightly dilated part of the rectum is the rectal ampulla.

Question 4

At what point does sigmoid become rectum?

Answer 4

S3

Question 5

How long is the rectum?

Answer 5

12cm

Question 6

What marks the end of the rectum?

Answer 6

Where the muscle coat is replaced by anal canal sphincters

Question 7

Why are there no sacculations in the rectum?

Answer 7

The three taenia coli have come together

Question 8

Does the rectum leave mesentery? What fascia surrounds the rectum?

Answer 8

No, nor appendages epiploicae, fascia propria

Question 9

What is the course of the rectum from S3?

Answer 9

Curves forward over coccyx and anococcygeal raphe behind the perineal body

Question 10

Where is the anorectal junction located?

Answer 10

3cm above the cutaneous margin, 5cm from the coccyx

Question 11

Describe the peritoneal coverings of the rectum

Answer 11

Anterior: The upper 2/3 is covered by peritoneum, the lower third is below the peritoneum that is reflected up to bladder/seminal vesicles or upper vagina.
Lateral: The upper 1/3 is covered by peritoneum
Posterior:

Question 12

What are the potential spaces anterior to the rectum called? How far above the anal margin are they found?

Answer 12

Rectovesical, 7.5cm from anal margin, and rectouterine, 5.5cm from anal margin.

Question 13

What is Denonvilliers?

Answer 13

A condensation of connective tissue intervening between the rectum and the anterior structures.

Question 14

What constitutes the lateral ligaments of the rectum?

Answer 14

Retroperitoneal tissue around the middle rectal vessels

Question 15

What are the posterolateral relations of the rectum?

Answer 15

S3,4,5 and coccyx, piriformis, lavator ani, ckoccygeus, anterior rami of lower 3 S/C(??) nerves, sympathetic trunk, pelvic splanchnic nerves and rectal vessels.

Question 16

What anchors the lower part of the rectum? To what?

Answer 16

Waldeyer’s fascia, to the lower sacrum

Question 17

What contributes to the rectourethralis muscles?

Answer 17

Some muscle fibres (from what?) leave the lower part of each side of the rectal ampulla to form the rectourethralis muscles

Question 18

Describe the blood supply of the rectum

Answer 18

Principally the superior rectal artery (a continuation from the IMA) and middle and inferior, and median sacral arteries

Question 19

What happens to the blood supply of the rectum at S3?

Answer 19

The superior rectal artery divides into various branches which supply the whole thickness of the muscle wall

Question 20

How does the middle rectal artery reach the rectum? From what does it arise?

Answer 20

Through the lateral rectal ligaments

Question 21

How does the inferior rectal artery reach the rectum? From what does it arise? Up to where does the inferior rectal artery supply?

Answer 21

The IRA penetrates the walls from the anal canal and may supply up to the peritoneal reflection.

Question 22

Describe the venous drainage of the rectum

Answer 22

Veins correspond to arteries but anastomose freely forming the internal and external rectal plexus.

The superior and inferior rectal veins are the most important, with drainage to both portal and systemic systems.

Question 23

Describe the lymphatic drainage of the rectum

Answer 23

Lymph passes back with the SRA, MRA and median sacral arteries. Lymphoid follicles ->
MSA: hollow of sacrum,
MRA: side wall of pelvis
Superior rectal and inferior mesenteric arterioes: pre-aortic nodes.

Question 24

What nerve types supply the rectum?

Answer 24

Sympathetic and parasympathetic, pain.

Question 25

Where does the sympathetic supply of the rectum come from?

Answer 25

From branches directly from the hyp0gastric plexus and fibres accompanying vessels

Question 26

Where does the parasympathetic supply of the rectum come from?

Answer 26

From S2,3 from pelvic splanchnic nerves

Question 27

What accompanies the sympathetic and parasympathetic nerves to the rectum?

Answer 27

Pain fibres appear to accompany both

Question 28

What does the rectum develop from?

Answer 28

The anal canal, with the anal membrane breaking down at the pectinate line

Question 29

What is the embryonic origin of the proximal part of the rectum?
What is the embryonic origin of the distal part of the rectum?

Answer 29

Endoderm, ectoderm.