Rectum (dave's notes) Flashcards Preview

Anatomy: pelvis and perineum (based on Dave's notes only so far) > Rectum (dave's notes) > Flashcards

Flashcards in Rectum (dave's notes) Deck (29):
1

Describe the curves of the rectum

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

2

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

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

3

What is the lowest part of the rectum called?

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

4

At what point does sigmoid become rectum?

S3

5

How long is the rectum?

12cm

6

What marks the end of the rectum?

Where the muscle coat is replaced by anal canal sphincters

7

Why are there no sacculations in the rectum?

The three taenia coli have come together

8

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

No, nor appendages epiploicae, fascia propria

9

What is the course of the rectum from S3?

Curves forward over coccyx and anococcygeal raphe behind the perineal body

10

Where is the anorectal junction located?

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

11

Describe the peritoneal coverings of the rectum

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:

12

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

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

13

What is Denonvilliers?

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

14

What constitutes the lateral ligaments of the rectum?

Retroperitoneal tissue around the middle rectal vessels

15

What are the posterolateral relations of the rectum?

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.

16

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

Waldeyer's fascia, to the lower sacrum

17

What contributes to the rectourethralis muscles?

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

18

Describe the blood supply of the rectum

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

19

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

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

20

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

Through the lateral rectal ligaments

21

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

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

22

Describe the venous drainage of the rectum

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.

23

Describe the lymphatic drainage of the rectum

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.

24

What nerve types supply the rectum?

Sympathetic and parasympathetic, pain.

25

Where does the sympathetic supply of the rectum come from?

From branches directly from the hyp0gastric plexus and fibres accompanying vessels

26

Where does the parasympathetic supply of the rectum come from?

From S2,3 from pelvic splanchnic nerves

27

What accompanies the sympathetic and parasympathetic nerves to the rectum?

Pain fibres appear to accompany both

28

What does the rectum develop from?

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

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?

Endoderm, ectoderm.