Small Bowel: Anatomy - Jejunum And Ileum Flashcards
(43 cards)
How long is the small bowel - cadaveric and in life?
6-7m cadaveric. 3-4m in life.
What are the first branches of the SMA, and where are they given off?
Inferior pancreaticoduodenal and middle colic, given off before passing over the uncinate process
Where does the SMA enter the root of the mesentary?
After passing over the uncinate process and D3/D4
What artery is sometimes part of a single trunk with the right colic?
The ileocolic
How many left sided intestinal branches does the SMA have?
15
What proportion of the small bowel is jejunum, ileum, and duodenum?
2/5 jejunum, 3/5ths ileum, 20cm duodenum
How do the 15 left-sided intestinal branches of the SMA continue after being given off?
Each fo the 15 divides into superior and inferior divisions, which then reanastomose with one another and form arcades.
What are the vasa recta?
End arteries to the small bowel
How many arcades of vasa recta are in the jejunum and ileum?
1-2 in the jejunum, and 5-6 in the ileum
What length of small bowel can survive without vasa recta?
2-4 cm before normal bowel colour is lost.
Small bowel is less tolerant of vasa recta division than the stomach. How do the stomach and esophagus differ to small bowel in this regard, and why?
The stomach and oesophagus have abundant intramural plexuses
Which of the left sided SMA branches has the longest branches? Why is this relevant in some surgical scenarios?
The fourth jejunal artery has the longest branches. Longer branches make this region best for mobilizing for loops/flaps.
What needs to be divided to bring a roux en y loop of jejunum up to the hiatus or chest?
Division of one, or two at most, of the left sided jejunal branches of the SMA
What happens when you divide more than 1-2 jejunal branches of the SMA to gain mobility?
The resulting ischaemic small bowel is greater than any mobility gained.
How far must the TI reach to create an ileal pouch? What increases the required length?
TI needs to reach 6cm below the inferior pubic ramus. Mucosa to my increases the length required.
What four steps can be used to increase reach of TI for an ileal pouch?
- Mobilise the small bowel mesentary to the duodenum
- Adjust the apex of the pouch for an extra 1-2cm
- Serial relaxing incisions in the peritoneum
- Further mobility may require division of main arteries - usually continuation of SMA for ileal pouch
What needs to be preserved in a total collecting if considering a future IPAA?
The ileocolic artery
What fibers to the small bowel come from the vagus nerve? What effect do they have?
Parasympathetic fibers.
Secretion, motility
Where does sympthetic innervation for the small bowel arise?
From splanchnic nerves, the ganglions of which are around the base of the SMA
Where do pain affronts for the small bowel (probably) run?
??with the sympathetics
What deposits of lymphatic tissue are throughout the small bowel?
Peyers patches
Give four steps for lymphatic drainage between small bowel mucosa and the thoracic ducts
Mucosa
1. Nodes adjacent to bowel
2. Regional nodes adjacent arcades
3. Superior mesenteric nodes
4. Cisternal chili
Thoracic dycts
What four features contribute to the enormous absorptive area of the small bowel?
- Small bowel length 4-6m
- Circular folds/plicae circularis
- Villi
- Microvilli
- Glycoprotein layer/glycocalyx
List the four layers of the intestinal wall
- Mucosa
- Submucosa
- Muscularis proprietary
- Serosa
