The Intestines Flashcards
(24 cards)
What does the small intestine consist of? What is its main function?
Consists of the duodenum (retroperitoneal), jejunum and ileum (peritoneal)
It is the primary site for absorption of nutrients from ingested material
What is the start and end of the small intestine?
Extends from the pylorus to the ileocaecal juction where the ileum joins the caecum
What are the key differences between the jejunum and ileum?
Jejunum: Located mainly in upper left quadrant Thick intestinal wall Longer vasa recta (straight arteries) Less arcades (arterial loops) Red in colour
Ileum: Located mainly in lower right quadrant Thin intestinal wall Shorter vasa recta More arcades Pink in colour
What is the function of the large intestine?
Where water is absorbed from the indigestible residues of the liquid chyme, converting it into semi-solid stool or faeces that is temporarily stored and allowed to accumulate until defecation occurs
What parts is the large intestine made up of?
Caecum, appendix, ascending, transverse and descending colon, sigmoid colon, rectum and anal canal
How can the large intestine be distinguished from the small intestine?
Omental appendices - small fatty, omentum like projections
Teniae coli - three distinct longitudinal bands
- Mesocolic tenia - to which the transverse and sigmoid mesocolons attach
- Omental tenia - to which the omental appendices attach
- Free tenia - to which neither mesocolon nor omental appendices are attached
Haustra - saccularions of the wall of the colon between the teniae
What arteries supply the duodenum?
Coeliac trunk -> gastroduodenal artery -> superior pancreaticduodenal artery
This supplies the duodenum proximal to the entry of the bile duct into the descending part of the duodenum
SMA -> inferior pancreaticduodenal artery
This supplies the duodenum distal to the entry of the bile duct
What is the venous drainage of the duodenum?
Veins of the duodenum follow the arteries and drain into the hepatic portal vein, some directly and some indirectly
What is the arterial supply of the jejunum and ileum?
SMA supplies the jejunum and ileum via jejunal and ileal arteries.
Lots of branches arise and they anastomose to form arcades and vasa recta arise from these to oxygenate the intestines
Where does the SMA usually arise from?
Arises from the abdominal aorta at L1 level, approx 1cm inferior to coeliac trunk and runs between the layers of mesentery
What is the venous drainage of the jejunum and ileum?
Superior mesenteric vein
SMV lies anterior and to the right of the SMA in the root of the mesentery. The SMV ends posterior to the neck of the pancreas, where it unites with the splenic vein to for the hepatic portal vein.
What is the ascending colon and proximal two thirds of the transverse colon supplied by?
The SMA
Ileocaecal artery
Right colic artery
Middle colic artery
What does the IMA supply?
The distal one third of the transverse colon, descending colon, and sigmoid colon
The left colic artery
Sigmoid artery
What is the marginal artery? And what does it supply?
Where the SMA and IMA anastomose. Supplies the whole colon and vasa recta arise from this to oxygenate it
Where do the SMV and IMv drain into?
The hepatic portal vein
What happens to the IMA and IMV below the pelvic brim?
IMA becomes the superior rectal artery and IMV becomes the superior rectal vein
What are the paracolic gutters?
The left and right paracolic gutters are peritoneal recesses on the posterior abdominal wall lying along side the ascending and descending colon. A less obvious medial paracolic gutter may be formed, especially on the right side, if the colon possesses a short mesentery for part of its length.
Where does the right paracolic gutter run from?
Runs from the superiolateral aspect of the hepatic flexure of the colon, down the lateral aspect of the ascending colon and around the caecum. It is continuous with the peritoneum as it descends into the pelvis over the pelvic brim. Superiorly it is continuous with the peritoneum which lines the hepatorenal pouch and through the epipoloic foramen, the lesser sac.
What is the recto-vesicle pouch?
It is a pocket that lies between the rectum and the urinary bladder in males.
What is the recto-vesicle pouch lined by?
Lined by peritoneum at the base in the rectoprostatic fascia.
What is significant about the recto-vesicle pouch when upright or supine?
The recto-vesicle pouch is at its lowest in the peritoneal cavity when standing. Because of this, peritoneal fluid and other fluids that enter the peritoneal cavity, including ascites, blood, pis, tend to collect in this pouch
What is important about the recto-vesicle pouch in women?
Women do not have a recto-vesicle pouch because the uterus lies in between the rectum and bladder.
Instead women have a recto-uterine pouch and a vesico-uterine pouch
Where is the recto-uterine pouch?
It is the deepest point of the peritoneal cavity, posterior to the uterus and anterior to the rectum. It is near the posterior for is if the vagina.
What is in the recto-uterine pouch?
Normally 1-3ml of fluid in the recto-uterine pouch throughout the menstrual cycle. After ovulation there is between 4-5ml of fluid
