L36: Abdominal Cavity II

Question 1

Components of small intestine. Relationship of parts to mesentery

Answer 1

1. ) Duodenum: 1st and 5th parts are intraperitoneal, 2nd-4th parts are secondarily retroperitoneal
2. ) Jejunum: intraperitoneal
3. ) Ileum: intraperitoneal

Question 2

What distinguishes small intestine from large intestine?

Answer 2

• Taenia coli, haustra, epiploic appendages

Question 3

Parts of large intestine. Relationship of parts to mesentery

Answer 3

1. ) Cecum: intraperitoneal
2. ) Ascending colon: secondarily retroperitoneal
3. ) Transverse colon: intraperitoneal
4. ) Descending colon: secondarily retroperitoneal
5. ) Sigmoid colon: intraperitoneal
6. ) Rectum: primarily retroperitoneal
7. ) Anus: primarily retroperitoneal

Question 4

Branches of celiac trunk

Answer 4

1.) Left gastric artery

2. ) Splenic artery:
   a. ) pancreatic arteries
   b. ) short gastric arteries
   c. ) left gastro-omental (gastroepiploic) artery
3. ) Common hepatic artery:
   a. ) gastroduodenal artery
   i. ) right gastro-omental (gastroepiploic) artery
   ii. ) superior pancreaticoduodenal artery
   iii. ) supraduodenal artery (sometimes absent)

b.) right gastric artery (sometimes branch of proper hepatic artery)

c. ) proper hepatic artery
i. ) right hepatic artery: cystic artery branches off here
ii. ) left hepatic artery

Question 5

Branches of SMA

Answer 5

1. ) inferior pancreaticoduodenal artery
2. ) intestinal branches
3. ) ileocolic artery
4. ) right colic artery
5. ) middle colic artery

Question 6

What arteries form the marginal artery?

Answer 6

• Marginal artery is an anastomotic artery formed by branches of ileocolic, right colic, middle colic and left colic. This artery gives rise to vasae rectae (straight vessels)

Question 7

Branches of IMA

Answer 7

1. ) left colic artery
2. ) sigmoid artery
3. ) superior rectal arteries

Question 8

Blood supply to stomach

Answer 8

1. ) left gastric artery: proximal portion of lesser curvature
2. ) short gastric arteries: to stomach closest to spleen
3. ) left gastro-omental (gastroepiploic) artery: left side of greater curvature
4. ) right gastro-omental (gastroepiploic) artery: right side of greater curvature
5. ) superior pancreaticoduodenal artery
6. ) right gastric artery: right lesser curvature

Question 9

Blood supply to pancreas

Answer 9

1. ) pancreatic arteries: neck, body and tail
2. ) superior pancreaticoduodenal artery
3. ) inferior pancreaticoduodenal artery: head of pancreas

Question 10

Blood supply to spleen

Answer 10

1.) splenic artery

Question 11

Blood supply to duodenum

Answer 11

1. ) superior pancreaticoduodenal artery: head of duodenum
2. ) supraduodenal artery (sometimes absent): superior aspect
3. ) inferior pancreaticoduodenal artery

Question 12

Blood supply to gallbladder

Answer 12

1.) Cystic artery

Question 13

Blood supply to liver

Answer 13

1. ) Right hepatic artery

2. ) Left hepatic artery

Question 14

Blood supply to jejunum

Answer 14

1.) intestinal branches from SMA

Question 15

Blood supply to ileum

Answer 15

1. ) intestinal branches from SMA

2. ) ileocolic artery: distal ileum

Question 16

Blood supply to cecum

Answer 16

1.) ileocolic artery

Question 17

Blood supply to ascending colon

Answer 17

1.) right colic artery

Question 18

Blood supply to transverse colon

Answer 18

1.) middle colic artery

Question 19

Blood supply to descending colon

Answer 19

1.) left colic artery

Question 20

Blood supply to sigmoid colon

Answer 20

1.) sigmoid artery

Question 21

Blood supply to proximal rectum

Answer 21

1.) superior rectal arteries

Question 22

If common hepatic artery is blocked, how will blood travel to liver?

Answer 22

• Common hepatic artery has gastroduodenal, right gastric and proper hepatic arteries as branches
• Right gastro-omental (gastroepiploic) artery off of gastroduodenal, anastomoses with left gastro-omental artery (off splenic, off celiac), therefore blood will travel via celiac, via splenic, via left gastro-omental into right-gastro-omental and back up into gastroduodenal into proper hepatic and into left hepatic artery

Question 23

Describe anastomoses within the gut

Answer 23

1. ) R & L gastro-omental (gastroepiploic) arteries
2. ) R & L gastric arteries
3. ) Sup & Inf pancreticoduodenal arteries
4. ) Inf pancreaticoduodenal and jejunal arteries
5. ) Marginal artery
6. ) Superior rectal arteries with middle and inferior rectal arteries

Question 24

Describe the structure of the hepatic portal system

Answer 24

• Foregut drains via splenic vein, Midgut drains via SMV, Hindgut drains via IMV
• IMV unites with splenic vein, which unites with SMV to form hepatic portal vein

Question 25

What is the definition of a portal system?

Answer 25

- Circulatory system between two capillary beds. In case of hepatic portal system, capillary beds of guts and sinusoids of liver.

Question 26

Is the entire gut drained into the hepatic portal system?

Answer 26

- No, lower esophagus to upper rectum.

Question 27

Suppositories are inserted into the rectum. They work by bypassing the hepatic portal system and conversion in the liver to an inert substance. How can this be?

Answer 27

- Only the upper 1/3rd of the rectum is drained via the hepatic portal system. Remainder is drained by the internal iliac vein that goes directly into the IVC, thus bypassing the liver.

Question 28

Describe how liver issues such as cirrhosis, hepatitis, liver tumors etc. can cause issues in blood flow through the hepatic portal system given the portocaval anastomoses

Answer 28

- Portal hypertension is increased pressure in the hepatic portal system as a result of decreased resistance to blood flow as the liver becomes diseased. Blood finds alternate routes via anastomoses: esophageal, rectal, umbilical and colonic. These individuals develop esophageal varices, hemorrhoids (external), caput medusa.

Question 29

Innervation of foregut

Answer 29

1. ) SNS: T5-9 presynaptics through sympathetic chain, pass through greater splanchnic nerve, synapse in celiac ganglia, postsynaptics follow branches of celiac trunk 2. ) PSNS: CN X (vagus) through celiac plexus without synapsing, synapse in ganglia in gut plexuses

Question 30

Innervation of midgut

Answer 30

1. ) SNS: T10-12 presynaptics through sympathetic chain, pass through lesser or least splanchnic (T10-11 and T12 respectively) nerves, synapse in superior mesenteric ganglion, postsynaptics follow branches of SMA 2. ) PSNS: CN X (vagus) through superior mesenteric plexus without synapsing, synapse in ganglia in gut plexuses

Question 31

Innervation of hindgut

Answer 31

1. ) SNS: L1-L2 presynaptics through sympathetic chain, pass through lumbar splanchnic nerves, synapse in inferior mesenteric ganglion, postsynaptics follow branches of IMA 2. ) PSNS: S2-S4 pass through sacral spinal nerves then through pelvic splanchnic nerves, branches to colon pass through hypogastric plexus and inferior mesenteric plexus, follow branches of IMA to target and synapse in ganglia in gut plexuses