337 - 339 - GI Anatomy

Question 1

What are the 4 main layers of the gut wall?

Answer 1

inside → outside:

1. Mucosa
2. Submucosa
3. Muscularis externa
4. Serosa
mnemonic: MSMS

Question 2

What are the 3 main structures within the gut mucosa, and what are their main functions?

Answer 2

1. Epithleium - absorption
2. Lamina propria - support
3. Muscularis mucosa - motility

Question 3

What important structure is contained within the submucosa?

Answer 3

Submucosal nerve plexus (Meissner)

Question 4

What are the 3 main components and corresponding functions of the muscularis externa?

Answer 4

1. Inner circular muscle layer - motility
2. Myenteric nerve plexus (Auerbach) - control mm. contractions
3. Outer longitudinal muscle layer - motility

Question 5

What is the function of the serosa? What is its name when it becomes retroperitoneal?

Answer 5

Function: support

Becomes the adventitia when retroperitoneal

Question 6

Differentiate between an ulcer and an erosion of the gut wall?

Answer 6

Erosions are in the mucosa only while ulcers can extend into the submucosa, inner or outer muscular layer (of the muscularis externa).

Question 7

What are the frequencies of basal electrical rhythm (slow waves) in the:

• Stomach?
• Duodenum?
• Ileum?

Answer 7

• Stomach: 3 waves/min
• Duodenum: 12 waves/min
• Ileum: 8-9 waves/min

Question 8

Histological appearance of the esophagus:

Answer 8

Nonkeratinized stratified squamous epithelium

Question 9

Histological appearance of the stomach:

Answer 9

gastric glands

Question 10

Histological appearance of the duodenum:

Answer 10

1. Villi and microvilla ↑ absorptive surface
2. Brunner glands (submucosa)
3. Crypts of Lieberkühn

Question 11

Histological appearance of the jejunum:

Answer 11

1. Plicae circularis

2. Crypts of Lieberkühn

Question 12

Histological appearance of the ileum:

Answer 12

1. Peyer patches (lamina propria, submucosa)
2. Plicae circulares (proximal ileum)
3. Crypts of Lieberkühn
4. Lots of goblet cells (largest # in the sm. intestine)

Question 13

Histological appearance of the colon:

Answer 13

1. Crypts of Lieberkün but no villi

2. Numerous goblet cells

Question 14

Give the vertebral levels for the following structures:

• Celiac trunk
• SMA
• L renal artery
• IMA
• Bifurcation of abd. aorta

Answer 14

• Celiac trunk - T12
• SMA - L1
• L renal artery - L1
• IMA - L3
• Bifurcation of abd. aorta - L4 (“bifourcation”)

Question 15

What artery comes off the abdominal aorta between the two branches of the common iliacs?

Answer 15

Median sacral artery

Question 16

Does the right or left testicular (ovarian) artery branch from the aorta first?

Answer 16

Left

Question 17

Which arteries come off the aorta on either side of the celiac trunk?

Answer 17

inferior phrenic arteries

Question 18

What artery comes off the aorta laterally to the SMA?

Answer 18

left middle suprarenal artery

Question 19

Arteries supplying GI structures branch from the aorta _______ (anteriorly/laterally) while those supplying non-GI structures branch ______ (anteriorly/laterally).

Answer 19

GI: anteriorly

non-GI: laterally

Question 20

What is the SMA syndrome?

Answer 20

When the transverse portion (third segment) of the duodenum is entrapped b/w the SMA and aorta → intestinal obstruction

Question 21

For the foregut, name the following:

• Artery:
• Parasympathetic innervation:
• Vertebral level:

Answer 21

• Artery: Celiac
• Parasympathetic innervation: Vagus
• Vertebral level: T12/L1

Question 22

For the midgut, name the following:

• Artery:
• Parasympathetic innervation:
• Vertebral level:

Answer 22

• Artery: SMA
• Parasympathetic innervation: Vagus
• Vertebral level: L1

Question 23

For the hindgut, name the following:

• Artery:
• Parasympathetic innervation:
• Vertebral level:

Answer 23

• Artery: IMA
• Parasympathetic innervation: Pelvic
• Vertebral level: L3

Question 24

What structures are supplied by the artery and nerves that supply the foregut?

Answer 24

Pharynx to proximal duodenum
Liver
Gallbladder
Pancreas
Spleen (mesoderm)

Question 25

What structures are supplied by the artery and nerves that supply the midgut?

Answer 25

Distal duodenum to proximal 2/3 of transverse colon

Question 26

What structures are supplied by the artery and nerves that supply the hindgut?

Answer 26

Distal 1/3 of transverse colon to upper portion of rectum (splenic flexure is a watershed region)

Question 27

What are the branches of the celiac trunk? What structure do these arteries supply?

Answer 27

1. common hepatic a. 2. splenic a. 3. left gastric a. - main blood supply of the stomach

Question 28

From what artery do the short gastric arteries arise?

Answer 28

Splenic artery

Question 29

In addition to the spleen, what structure would you be concerned about if the splenic artery were blocked?

Answer 29

the stomach: the short gastrics that arise from the splenic artery have poor anastomoses

Question 30

Which arteries travel along the greater curvature of the stomach? Describe the strength of their anastomoses.

Answer 30

Left and right gastroepiploic arteries; strong anastomoses

Question 31

From what main arteries do the gastroepiploic arteries arise?

Answer 31

Left: splenic artery Right: gastroduodenal artery

Question 32

What are the branches of the common hepatic artery?

Answer 32

hepatic artery proper | gastroduodenal artery

Question 33

What are the branches of the gastroduodenal artery?

Answer 33

1. anterior superior pancreaticoduodenal artery 2. posterior superior pancreaticoduodenal artery 3. right gastroepiploic artery

Question 34

Where do the left and right gastric arteries arise? Describe their anastomoses in terms of strength.

Answer 34

Left: celiac trunk Right: hepatic artery proper (less commonly from the common hepatic artery) Strong anastomoses

Question 35

What artery compensates through anastomoses when the superior gastric a. (from interal thoracic/mammary) is blocked (and vice-versa)?

Answer 35

inferior epigastric a. (from external iliac)

Question 36

What artery compensates through anastomoses when the superior pancreaticoduodenal a. (from celiac trunk) is blocked (and vice-versa)?

Answer 36

inferior pancreaticoduodenal a. (from SMA)

Question 37

What artery compensates through anastomoses when the middle colic a. (from SMA) is blocked (and vice-versa)?

Answer 37

left colic a. (from IMA)

Question 38

What artery compensates through anastomoses when the superior rectal a. (from IMA) is blocked (and vice-versa)?

Answer 38

middle and inferior rectal a. (from internal iliac)