rectum and anal canal Flashcards Preview

MD3002 post MSA > rectum and anal canal > Flashcards

Flashcards in rectum and anal canal Deck (34):
1

where does the rectum start

S3

2

describe the shape of the rectum

has lateral concavities that form left, right, left rectal folds
the lower part is slightly dilated- the rectal ampulla
the middle concavity on the right is most pronounced

3

why is the first concavity on the left

because the sigmoid leads to the rectum from the left

4

what is found next to the rectum

pararectal fossae

5

what is the pouch of douglas

the rectouterine pouch

6

describe the peritoneal covering of the rectum

covered by mesorectum which is not a mesentery.
the upper third of the rectum is covered front and sides by peritoneum
the middle third is only covered in front
the lower third has no peritoneal covering

contains sup rectal artery and veins plus lymph nodes and nerves

7

what is denonvilliers fascia

rectoprostatic fascia in the lower part of the rectovesical pouch

8

how long is the rectum

12 cm

9

what are the anterior relations of the rectum

bladder, vas, seminal vesical, prostate, pelvic floor

10

what nerves are at risk in rectal surgery

urogenital nerves and vessels

11

describe the internal sphincter

derived from circular smooth muscle, autonomic, ends at the intersphincteric groove

12

describe the external sphincter

striated muscle, deep, superficial and subcutaneous parts

13

what muscles surround the anus

puborectalis and pubococcygeus

14

what muscle forms a sling around the anorectal junction

puborectalis

15

what is the anococcygeal ligament

formed by the fused levator ani and attaches the anal canal to the coccyx

16

what does the external sphincter fuse with in the female

puborectalis, anococcygeal ligament and the perineal body

17

what are the features of the inside of the anus

mucous membrane and submucosa are loose, mobile and distensible
rich underlying vasculature

18

how is anal closure maintained

anal cushions and internal sphincter

19

what is the superior rectal artery a branch of

inferior mesenteric

20

what is the middle rectal artery a branch of

internal iliac- may be absent

21

what is the inferior rectal artery a branch of

internal pudendal

may also be a contribution from the median sacral which may bleed during surgery

22

describe the rectoanal veins

mirror arteries
form external and internal venous plexuses which form a portosystemic anastomosis

this is due to sup. rect veins to inf. mesenteric and middle rectal veins going to the internal iliac

23

what is the lymph drainage of the rectum

inf mesenteric nodes

internal iliac nodes

superficial inguinal nodes for distal anal canal

24

what is the parasympathetic supply of the rectum

pelvic splanchnics from S2,3,4 Going to the pelvic plexus

25

what is the function of the pelvic plexus

caries recto anal sensations and controls the internal sphincter

26

what plexus forms the pelvic plexus

superior hypogastric plexus

27

what controls the external sphincter and adjacent pelvic flood muscles and gives sensation to the distal anal canal

inferior rectal which is derived from the internal pudendal nerve from S2-4

28

what happens during defecation

cortical inhibition is released
abdo pressure is increased
puborectalis relaxes, allows the rectal angle to straighten
external sphincter relaxes (s2-4)
lower colon and rectum contract while the internal sphincter relaxes

29

what might cause incontinence

cord lesions above S2-4
loss of cortical control
damage to external sphincter during surgery
entrapment of the pudendal nerve

30

what is the ischio anal fossa

fat filled pyramid region below levator ani and either side of the anal canal to allow distension during defecation

31

where does the pudendal neurovascular bundle lie

laterally in alcock's canal (obturator fascia)

32

what does the inferior rectal NVB supply

external sphincter and anal canal sensation

33

what muscle inserts onto the anococcygeal body

iliococcygeus, pubococcygeus and ishiococcygeus

34

where is alcocks canal

overlies obturator internus and lateral to the rectum