EXAM #1: LOWER GI ANATOMY Flashcards
What vagal trunk runs anterior to the esophagus?
Left
What vagal trunk runs posterior to the esophagus?
Right
What is the eponym for the anterior gastric nerve? What nerve is this a branch of?
Anterior nerve of Latarjet, a branch of the left vagus
What is the eponym for the posterior gastric nerve? What nerve is this a branch of?
Posterior nerve of Latarjet, a branch of the right vagus
What is the Criminal Nerve of Grassi?
A branch of the posterior nerve of Latarjet
What surgical procedure can be performed for Refractory PUD?
Highly selective vagotomy of:
1) Anterior and posterior nerves of Latarjet
2) Criminal Nerve of Grassi
Note that this denervates the body and fundus of the stomach (containing parietal cells), while maintaining innervation of the other regions
Draw the direction of lymph flow in the stomach.
N/A
How can gastric cancer progress to pacreatic duct obstruction?
1) Metastasis to the lymph nodes from the lower portion of the greater curvature of the stomach
2) Mass effect from posterior gastric tumor
What are the three surface modifications seen in the small intestine? How much do each of these modifications increase the surface area?
1) Plica circularis (x3)
2) Villus (x10)
3) Microvillus (x20)
What surface modification of the small intestine is thickened in enteritis?
Plicae circularis
What happens to the surface modifications of the small intestines in gluten enteropathy?
Loss of modifications i.e. villi and microvilli
What are the four signature histologic features of gluten enteropathy?
1) Enterocytes are disarrayed
2) Villus atrophy
3) Crypt hyperplasia
4) Inflammation of lamina propria
What is the first segment of the duodenum?
Bulb/ampulla
Where are most duodenal peptic ulcers found?
First part of the duodenum
What structures may be damaged if there is perforation of a posterior duodenal ulcer?
1) Pancreas
2) Gastroduodenal a.
What results from an anterior duodenal ulcer perforation?
Air accumulation between diaphragm and anterior wall of the liver
What is the Ligament of Treitz?
Suspensory muscle of the duodenum that facilitates movement of chyme from Part 4 into the Jejunum
What vertebral level is the SMA adjacent to?
L1
If an embolus leaves the aorta and is going to enter the celiac trunk or SMA, which is more likely?
SMA b/c:
- Celiac trunk branches perpendicularly
- SMA branches obliquely
What is the “Nutcracker” effect of the SMA on the 3rd part of the duodenum?
- Body fat fills the angle between SMA and 3rd part of the duodenum
- Loss of fat can cause obstruction of duodenum by SMA clamping down
What is Intussusception?
Telescoping of part of the bowel telescoping into another part of the bowel
What is the consequence of Intusssception?
Ischemia/necrosis of the telescoped segment b/c of a build-up of venous pressure as blood cannot leave the segment
What is the appearance of stool in Intussusception?
“Currant Jelly”
Necrotic cells sloughing off contain blood*
What clinical point corresponds to the appendix?
McBurney’s Point
What is the definition of McBurney’s point?
1/3 the distance from the ASIS to umbilicus
What causes appendicitis?
1) Fecal obstruction of the lumen of the appendix
2) Bacterial infection
Simple columnar epithelium with goblet cells produce mucous that is prevented from flowing from the lumen of the appendix to the cecum. Tissue pressure of the appendix increases and chokes off blood supply
What are diverticula?
Outpouching of the wall of the colon
What type of diverticula are seen in the colon?
False
Outpouching of the mucosa and submucosa vs. a true diverticula that involves all of the walls
Describe the pathogenesis of diverticula i.e. what causes the weakness in the wall of the colon that leads to the development of diverticula?
1) Large intestine contains tenia coli; between these three bands are sites of weakness for diverticula formation
2) Vasa recta on the mesenteric side of the colon are sites of potential weakness
Why is the rectum rarely involved in the formation of diverticula?
No tenia coli; these “splay” to form a complete outer longitudinal layer
What are the anatomical differences between ulcerative colitis and IBD?
Ulcerative colitis=
- Colon only
- Mucosa and submucosa
IBD=
- Any part of the GI tube
- Involves all walls
What is a Crohn Enterocutaneous Fistula?
Fistula between colon and anterior abdominal wall
Which part of the colon is more likely to be involved in malignant obstruction? Why?
Left b/c of:
- Smaller diameter
- More “fluid” fecal mass on right side (proximal)
Colon cancer on which side of the colon is more likely to result in bright red blood per rectum?
Left
Outline the arterial blood supply to the colon.
N/A
Which segment of the colon is most vulnerable to ischemia?
“Critical Point of Griffiths” i.e. the left colic flexure where the marginal artery is the narrowest
What is the “Arc of Riolan?”
A branch from the Middle Colic Artery to IMA
Where would you ligate the IMA in open repair of an AAA?
Proximal to the Arc of Riolan
What is the Triangle of Calot?
1) Cystic artery
2) Cystic duct
3) Common hepatic duct
When do you define the Triangle of Calot?
Prior to Cholecystectomy
