EXAM #1: LOWER GI ANATOMY

Question 1

What vagal trunk runs anterior to the esophagus?

Answer 1

Left

Question 2

What vagal trunk runs posterior to the esophagus?

Answer 2

Right

Question 3

What is the eponym for the anterior gastric nerve? What nerve is this a branch of?

Answer 3

Anterior nerve of Latarjet, a branch of the left vagus

Question 4

What is the eponym for the posterior gastric nerve? What nerve is this a branch of?

Answer 4

Posterior nerve of Latarjet, a branch of the right vagus

Question 5

What is the Criminal Nerve of Grassi?

Answer 5

A branch of the posterior nerve of Latarjet

Question 6

What surgical procedure can be performed for Refractory PUD?

Answer 6

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

Question 7

Draw the direction of lymph flow in the stomach.

Answer 7

N/A

Question 8

How can gastric cancer progress to pacreatic duct obstruction?

Answer 8

1) Metastasis to the lymph nodes from the lower portion of the greater curvature of the stomach
2) Mass effect from posterior gastric tumor

Question 9

What are the three surface modifications seen in the small intestine? How much do each of these modifications increase the surface area?

Answer 9

1) Plica circularis (x3)
2) Villus (x10)
3) Microvillus (x20)

Question 10

What surface modification of the small intestine is thickened in enteritis?

Answer 10

Plicae circularis

Question 11

What happens to the surface modifications of the small intestines in gluten enteropathy?

Answer 11

Loss of modifications i.e. villi and microvilli

Question 12

What are the four signature histologic features of gluten enteropathy?

Answer 12

1) Enterocytes are disarrayed
2) Villus atrophy
3) Crypt hyperplasia
4) Inflammation of lamina propria

Question 13

What is the first segment of the duodenum?

Answer 13

Bulb/ampulla

Question 14

Where are most duodenal peptic ulcers found?

Answer 14

First part of the duodenum

Question 15

What structures may be damaged if there is perforation of a posterior duodenal ulcer?

Answer 15

1) Pancreas

2) Gastroduodenal a.

Question 16

What results from an anterior duodenal ulcer perforation?

Answer 16

Air accumulation between diaphragm and anterior wall of the liver

Question 17

What is the Ligament of Treitz?

Answer 17

Suspensory muscle of the duodenum that facilitates movement of chyme from Part 4 into the Jejunum

Question 18

What vertebral level is the SMA adjacent to?

Answer 18

L1

Question 19

If an embolus leaves the aorta and is going to enter the celiac trunk or SMA, which is more likely?

Answer 19

SMA b/c:

• Celiac trunk branches perpendicularly
• SMA branches obliquely

Question 20

What is the “Nutcracker” effect of the SMA on the 3rd part of the duodenum?

Answer 20

• 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

Question 21

What is Intussusception?

Answer 21

Telescoping of part of the bowel telescoping into another part of the bowel

Question 22

What is the consequence of Intusssception?

Answer 22

Ischemia/necrosis of the telescoped segment b/c of a build-up of venous pressure as blood cannot leave the segment

Question 23

What is the appearance of stool in Intussusception?

Answer 23

“Currant Jelly”

Necrotic cells sloughing off contain blood*

Question 24

What clinical point corresponds to the appendix?

Answer 24

McBurney’s Point

Question 25

What is the definition of McBurney’s point?

Answer 25

1/3 the distance from the ASIS to umbilicus

Question 26

What causes appendicitis?

Answer 26

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

Question 27

What are diverticula?

Answer 27

Outpouching of the wall of the colon

Question 28

What type of diverticula are seen in the colon?

Answer 28

False

Outpouching of the mucosa and submucosa vs. a true diverticula that involves all of the walls

Question 29

Describe the pathogenesis of diverticula i.e. what causes the weakness in the wall of the colon that leads to the development of diverticula?

Answer 29

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

Question 30

Why is the rectum rarely involved in the formation of diverticula?

Answer 30

No tenia coli; these “splay” to form a complete outer longitudinal layer

Question 31

What are the anatomical differences between ulcerative colitis and IBD?

Answer 31

Ulcerative colitis=

• Colon only
• Mucosa and submucosa

IBD=

• Any part of the GI tube
• Involves all walls

Question 32

What is a Crohn Enterocutaneous Fistula?

Answer 32

Fistula between colon and anterior abdominal wall

Question 33

Which part of the colon is more likely to be involved in malignant obstruction? Why?

Answer 33

Left b/c of:

• Smaller diameter
• More “fluid” fecal mass on right side (proximal)

Question 34

Colon cancer on which side of the colon is more likely to result in bright red blood per rectum?

Answer 34

Left

Question 35

Outline the arterial blood supply to the colon.

Answer 35

N/A

Question 36

Which segment of the colon is most vulnerable to ischemia?

Answer 36

“Critical Point of Griffiths” i.e. the left colic flexure where the marginal artery is the narrowest

Question 37

What is the “Arc of Riolan?”

Answer 37

A branch from the Middle Colic Artery to IMA

Question 38

Where would you ligate the IMA in open repair of an AAA?

Answer 38

Proximal to the Arc of Riolan

Question 39

What is the Triangle of Calot?

Answer 39

1) Cystic artery
2) Cystic duct
3) Common hepatic duct

Question 40

When do you define the Triangle of Calot?

Answer 40

Prior to Cholecystectomy