Rectum

Question 1

What is the rectum?

Answer 1

pelvic end of alimentary tract where feces accumulate prior to defecation

Question 2

Where is the rectum located?

Answer 2

located between sigmoid colon and anal canal

Question 3

Rectosigmoid junction located anterior to what?

Answer 3

S3

Question 4

Is the rectum retro/intra/extra peritoneal?

Answer 4

retroperitoneal

Question 5

Which structure expands into a continuous layer onto the rectum?

Answer 5

Teniae coli of sigmoid colon

Question 6

Does the rectum have epiploic appendages, haustra, or sacculations?

Answer 6

no, they are absent

Question 7

What is the sacral flexure?

Answer 7

rectum follows contour of sacrum and coccyx

Question 8

What is the anorectal flexure?

Answer 8

shape turn at coccyx where rectum pierces pelvic diaphragm

Question 9

What is approximate 80degree posterior turn of the anorectal flexure important for?

Answer 9

maintaining fecal continence (control of bowels)

Question 10

What muscle maintains tonus of the anorectal flexure?

Answer 10

Puborectalis m.

- must actively contract to resist peristaltic contractions in rectum and prevent defecation

Question 11

What needs to happen for conscious defecation to occur?

Answer 11

relaxation of puborectalis m.

Question 12

what are the 3 sharp lateral flexures present in rectum and what do they correspond to?

Answer 12

Superior, intermediate and inferior

- correspond to Transverse rectal folds of the mucosa and submucosa

Question 13

What is the ampulla of the rectum?

Answer 13

dilatable terminal region lying above and supported by levator ani m.
-Relaxes to hold accumulating fecal material prior to defecation

Question 14

Yo, the superior 3rd of rectum is retroperitoneal and inferior 3rd is subperitoneal

Answer 14

random part in the notes…. guess there is no middle area

Question 15

What structures provide space for rectum to distend as it fills with feces? (male vs. female)

Answer 15

Rectovesical pouch (male)
Rectouterine pouch (females)
Pararectal fossae

Question 16

What forms the peritoneal reflection in males?

Answer 16

rectovesical pouch

Question 17

What forms the peritoneal reflection in females?

Answer 17

rectouterine pouch

Question 18

What forms as the lateral peritoneal reflection in both sexes?

Answer 18

Pararectal fossae

Question 19

What structures are associated with rectum posteriorly? (both sexes)

Answer 19

• sacral vertebrae and coccyx
• sacral plexuses and inferior ends of sympathetic trunks
• median sacral a. and v.

Question 20

What structures are associated with the rectum anteriorly for males?

Answer 20

-Fundus of urinary bladder and terminal parts of ureters
-Ductus deferens, seminal vesicles and prostate
(separated from these structures by rectovesical pouch)

Question 21

What structures are associated with the rectum anteriorly for females?

Answer 21

Vagina, posterior fornix, and cervix of uterus

separated from these structures by rectouterine pouch

Question 22

What is the arterial supply to rectum?

Answer 22

Superior rectal a.
Middle rectal a.
inferior rectal a.

Question 23

Superior rectal a.

Answer 23

Branch from Inferior mesenteric a.

-supplies proximal part of sacrum

Question 24

Middle rectal a.

Answer 24

Branches from internal iliac (anterior division)

Question 25

Inferior rectal a.

Answer 25

Branches from internal pudendal a. | -supplies anorectal junction and anal canal

Question 26

What is the venous drainage of the rectum?

Answer 26

Superior rectal v. Middle rectal v. Inferior rectal v.

Question 27

Superior rectal v.

Answer 27

drains hepatic portal venous system

Question 28

Middle and inferior rectal v.v.

Answer 28

drains to systemic system via internal iliac v. | -anastomoses b/t these veins create an important portacaval anastomosis

Question 29

What are enlarged veins around the inferior rectum and anal canal?

Answer 29

Hemorrhoids

Question 30

What are hemorrhoids?

Answer 30

Dilated and prolapsed veins of rectal venous plexus

Question 31

What are predisposing factors of hemorrhoids?

Answer 31

those that cause increased intra-abdominal pressure - E.g. pregnancy or chronic constipation - Can occur in cases of portal hypertension (rectal v.v. are an anastomosis b/t portal and systemic system)

Question 32

What are the types of hemorrhoids?

Answer 32

Internal or External

Question 33

Internal hemorrhoids

Answer 33

probably due to breakdown of muscularis mucosa | -prolapse into lumen of anal canal and ulcerate (blood in stool)

Question 34

External hemorrhoids

Answer 34

Involves external rectal venous plexus and are covered by skin

Question 35

What is the superior lymphatic drainage of the rectum?

Answer 35

drains through pararectal to inferior mesenteric and lumbar nodes

Question 36

What is the inferior lymphatic drainage of the rectum?

Answer 36

drains though internal iliac nodes

Question 37

What is the sympathetic innervation of the rectum?

Answer 37

via lumbar splanchnic n. through superior hypogastric plexus - Follow superior recta a. (branch of Inferior mesenteric a.) - Possibly vasomotor but not functionally significant

Question 38

What is the parasympathetic innervation of the rectum?

Answer 38

via pelvic splanchnic n. through inferior hypogastric plexus | -motor fibers to rectal muscularis externa

Question 39

Visceral afferents pass retrogradely through what?

Answer 39

pelvic splanchnic n. S2-S4 | -both pain and/or distention (indicating gas or feces)

Question 40

What n. mediated innervation controls defecation?

Answer 40

pelvic splanchnic n.

Question 41

What happens when ampulla is empty?

Answer 41

Internal anal sphincter m. contracted | External anal sphincter m. relaxed

Question 42

What happens when feces accumulates in ampulla and sufficiently distends it?

Answer 42

Internal anal sphincter m. reflexively relaxes External anal sphincter m. reflexively contracts -Initiated by visceral afferents in pelvic splanchnic n.

Question 43

What is required for defecation?

Answer 43

Requires voluntary override of reflexive external anal sphincter m. contraction -Puborectalis m. also must voluntarily relax

Question 44

What causes movement of feces?

Answer 44

Parasympathetic stimulation increases peristaltic activity in rectum -movement assisted by increased abdominal pressure

Question 45

Rectal examination, and what are you feeling for in males and females?

Answer 45

Provides opportunity to palpate many clinically significant structures - Males: prostate and seminal vesicles - Females: cervix - Both: sacrum, coccyx, ischial spines and tuberositie

Question 46

What pathologies are you looking for during a rectal exam?

Answer 46

enlarged nodes, thickened ureters or abscesses

Question 47

What is used to visualize rectal lumen and remove lesions?

Answer 47

Proctoscope