Rectum and Anal Canal Flashcards
What is the function of the rectum?
Storage organ for faeces.
Is the rectum intra or retero peritoneal?
Reteroperitoneal as it sits in the pelvis
Name the two pouches in the female pelvis?
Retectouterine pouch (Pouch of Douglas) - between rectum and uterus Vesicouterine pouch - between bladder and uterus
Name the pouch in the male pelvis.
Rectovesicle pouch - between rectum and bladder
Name the boundaries of the anal triangle.
Both sides by the sacrotuberous ligament.
Superior roof = levator ani muscle
What is the ischioanal fossa?
Fossa = shallow depression/hole
Fat-filled wedge shaped space lateral to the anal canal.
Allows for area of expansion of the anal canal to allow faces to pass through.
What are structural features of the rectum lining?
No teniae coli.
Has a complete layer of longitudinal muscle.
No plicae circulares.
Give some features of the anal canal.
Contains anal collumns - longitundinal folds of mucosa - enables expansion of the anal canal.
What is the pectinate line?
Marks the division between the gut and the proctodeum.
What is Hilton’s White line?
Demarkation where internal sphincter ends.
Transition from internal to external(skin)
What type of muscle is the internal anal sphincter and its innervation?
Smooth muscle - under autonomic control.
S2, 3 and 4 keeps the shit off the floor.
Parasympathetic control.
What type of muscle is the external anal sphincter and its innervation?
Skeletal muscle - under somatic (voluntary) control.
Supplied by the pudendal nerve (nerve roots S2,3,4)
What is the arterial supply of the rectum?
Upper 1/3 = superior rectal artery (branch of the superior emsenteric artery)
Middle 1/3 = middle rectal artery (branch of the internal iliac artery)
Lower 1/3 = inferior rectal artery (branch of the internal pudendal artery)
What is the venous drainage of the rectum?
Superior rectal vein drains into the superior mesenteric vein which drains into the hepatic portal.
Middle rectal artery and inferior rectal artery drain into the internal iliac which drains into the common iliac and into the inferior vena cava.
What is an internal haemorrhoid?
Bulging out above the pectinate line. May rupture the mucosal wall causing bleeding
