Rectum and Anal Canal Flashcards
What is the course of the rectum
It begins as continuation of sigmoid colon in front of third sacral vertebrae and ends slightly below the tip of coccyx
What is posterior to the rectum in both males and females
sacrum, coccyx ,
median sacral vessels, Sympathetic chain and sacral plexus
What is anterior to the rectum in males
base of urinary bladder,
seminal vesicles, Vas deferens and prostate
What is anterior to the rectum in females
posterior vaginal wall
What are the muscular folds in the rectum. Which one is temporary, which one is vice versa.
Longitudinal or temporary folds
Transverse or permanent folds
(Houston’s valves)
How many valves are in the permanent mucus folds
Four (1st, 2nd, 3rd, 4th)
Which valves in the permanent mucus folds are constant and where are they located
First valve (S3) and Third valve (S5)
Arterial supply of the rectum
Superior rectal, middle rectal and median sacral artery
Venous drainage of the rectum
Superior rectal and middle rectal veins
Lymphatic drainage of the rectum
upper part – inferior mesenteric group Lower part – internal iliac nodes
Nerve supply of the rectum
Parasympathetic – S2,S3,S4
Sympathetic – L1,L2
Where does the anal canal begin
It begins at ano-rectal junction
Zones of the interior anal canal
Upper area (pectinate zone)
Intermediate area (pecten)
Lower area (anal verge)
What is contained within the upper area of the internal anal canal
Anal columns (columns of morgagni Anal valves (valves of ball) Anal papillae Anal sinuses Anal glands Pectinate line
What is contained within the intermediate area of the internal anal canal
Extends from Pectinate line to Hinton’s
white line
Lined by non keratinised squamous stratified epithelium
Presence of internal rectal venous plexus
What is contained within the lower area of the internal anal canal
Lined by true skin and presence of skin folds
Arterial Supply of the anal canal
Superior rectal artery – branch of inferior mesenteric artery
Middle rectal artery – branch of internal iliac artery
Inferior rectal artery – branch of internal pudendal artery (internal iliac artery)
Venous drainage of the anal canal above the pectinate line
Internal rectal venous plexus drains into superior rectal vein, which continuous as inferior mesenteric vein
then into portal vein
Venous drainage of the anal canal below the pectinate line
External venous plexus drains into inferior rectal vein then into Internal iliac vein then into IVC
From which embryologic derivative does above the pectinate line develop
endoderm
From which embryologic derivative does below the pectinate line develop
ectoderm
Sphincter Ani Internus has which muscles and what kind of movement
Inner circular muscles of rectum and t is iinvoluntary
Characteristics of Internal piles or true piles
occurs above pectinate line
They are painless and bleed profusely
Characteristics of External piles or false piles
occurs below pectinate line
They are very painful with minimal bleeding
