Gross Anatomy of Alimentary Tract

Question 1

Parasympathetic innervation of the foregut, midgut, and hindgut?

Answer 1

Foregut: Vagus nerve
Midgut: Vagus nerve
Hindgut: Pelvic nerves (S2,3,4)

Question 2

Sympathetic spinal nerve levels for each foregut, midgut, and hindgut?

Answer 2

Foregut: T5-T9
Midgut: T10-T12
Hindgut: L1-L3

Question 3

What functions do the sympathetics have in the gut?

Answer 3

Diverting blood away.

Important for referred pain.

Question 4

3 different types of mesentery remnants?

Answer 4

Ligaments
Omentum
“Meso-“ things (eg. mesocolon)

Question 5

What’s the role of the cricopharyngeus muscle?

Answer 5

Acts like a sphincter at the top of the esophagus (at the cervical constriction).

Question 6

3 areas of constriction of the esophagus? (Approximate spinal cord levels?)

Answer 6

Cervical constriction - C6
Thoracic (aka broncho-aortic) - T4
Diaphragmatic (aka LES) - T11

Question 7

What kind of muscle is in the esophagus? What nerves control it?

Answer 7

Skeletal at the top, smooth for most of it.

It’s all vagus nerve innervation.

Question 8

4 anatomic divisions of the stomach?

Answer 8

Cardiac
Fundus
Body
Pylorus
(Fundus and body aren't distinguished histologically)

Question 9

What muscle layer does the stomach have that other parts of the gut don’t?

Answer 9

The innermost oblique - helps grind things up.

Question 10

At what level is the esophageal hiatus? What else is there?

Answer 10

T10 - that’s also where the esophageal sphincter is.

Question 11

How does the mucosa change from esophagus to stomach? What is this called?

Answer 11

Changes from squamous epithelium to columnar. The transition is called the Z-line because it’s zig-zagged.

Question 12

If you get a perforating ulcer through the posterior wall of the stomach, where will the contents end up?

Answer 12

They’ll end up int he lesser sac (aka. omental bursa).

Question 13

Review: 3 major branches of the celiac trunk?

Answer 13

Left gastric a.
Common hepatic a.
Splenic a.

Question 14

What is the dual blood supply of the lesser curvature of the stomach?

Answer 14

Left gastric a.

Right gastric a. (comes off the common hepatic a.)

Question 15

What is the dual blood supply of the greater curvature of the stomach?

Answer 15

L. gastroepiploic a. (off of splenic a.)

R. gastroepiploic a. (off the gastroduoenal a. off the common hepatic a.)

Question 16

Where do the left and right vagus nerves go around the the level of the stomach?

Answer 16

Left becomes anterior vagal trunk / plexus.

Right becomes posterior.

Question 17

What vessels run between the head/neck of the pancreas and the duodenum?

Answer 17

Superior mesenteric a.

Superior mesenteric v.

Question 18

When looking at it from inside, what is the name of the structure where the ampulla of vater drains into the duodenum?

Answer 18

The major duodenal papilla.

Question 19

What are the big ridges in the jejunum called?

Answer 19

Plicae circularis.

Question 20

How does the ileum vary grossly from the jejunum, on the inside?

Answer 20

The luminal surface is much smoother in the ileum.

Question 21

Review: How does the configuration of the vasa recta vary between jejunum and ileum?

Answer 21

Jejunum: simple arcades, long vasa recta.
Ileum - complex arcade, short vasa recta.
(shorter name, shorter vasa recta?)

Question 22

What’s the longitudinal muscle of the colon?

Answer 22

Tenia coli…

Question 23

From supplying proximal bowel to distal bowel, what are the 3 major branches of the SMA?

Answer 23

Ileocolic a.
Right colic a.
Middle colic a.
(jejunal aa. feed vasa recta of the jejunum)

Question 24

From supplying proximal bowel to distal bowel, what are the 3 major branches of the IMA?

Answer 24

Left colic a.
Sigmoid aa.
Superior rectal a.

Question 25

What is the artery running parallel to the colon with lots of collateral blood flow called?

Answer 25

The marginal a.

Question 26

Review: Which area of the colon is most susceptible to ischemia when blood pressure drops?

Answer 26

The junction between midgut and hindgut (2/3 along the transverse colon), as this is at the end of each the SMA’s and IMA’s domains.

Question 27

Should you be pretty familiar with the radiology stuff here?

Answer 27

Yeah…