GI VASCULAR SUPPLY & INNERVATION (anatomy)

Question 1

The digestive system within the abdomen consists of derivatives of the embryonic gut supplied by unpaired……….. branches of the abdominal aorta (See attached pic).

The caudal foregut is supplied by the…………………

Answer 1

ventral celiac trunk (celiac artery)

Question 2

Midgut is supplied by the………………… artery.

Answer 2

superior mesenteric

Question 3

Hindgut is supplied by the……………….. artery.

Answer 3

inferior mesenteric

Question 4

The embryonic foregut forms what in an adult?

Answer 4

• Abdominal portion of the esophagus
• Stomach
• Duodenum, as far as its union with the common bile and pancreatic ducts (middle of descending part)
• Liver and gallbladder
• Pancreas
• Spleen, which is not part of the digestive tract but is closely related by position

Question 5

What are the branches of the celiac trunk that supply derivatives of the embryonic caudal foregut?

Answer 5

• Left gastric artery
• Splenic artery
• Common hepatic artery

Question 6

What does the left gastric artery supply?

Answer 6

the stomach and the lower esophagus

Question 7

What does the splenic artery supply?

Answer 7

– Supplies the neck, body, and tail of the pancreas and the spleen

– Also sends branches to the stomach

Question 8

The common hepatic artery branches into what arteries, and what do they supply?

Answer 8

– Gastroduodenal artery: supplies the stomach, head of the pancreas, and duodenum.

– Proper hepatic artery: supplies the liver and gallbladder; it also sends a branch to the stomach.

Question 9

Duodenal ulcers usually occur in the……….. part of the duodenum.

Answer 9

superior

Question 10

Posterior duodenal ulcers erode directly onto the…………………. artery or more commonly on posterior superior pancreaticoduodenalartery (a branch of……………..). This produces massive hemorrhage which can be fatal!!!

Answer 10

gastroduodenal

gastroduodenal

Question 11

Anterior duodenal ulcers erode into what?

Answer 11

into the peritoneal cavity (peritonitis caused leads to adhesion of the greater omentum).

Question 12

The embryonic midgutforms what in the adult?

Answer 12

• Duodenum (distal to its union with the bile and pancreatic ducts)
• Jejunum and ileum
• Cecum and appendix
• Ascending colon
• Transverse colon

Question 13

Branches of the superior mesenteric artery supplying derivatives of the embryonic midgut are:

• Inferior pancreaticoduodenal artery
• Intestinal branches
• Middle colic artery
• Right colic artery
• Ileocolic artery

What do they each lead to?

Answer 13

• Inferior pancreaticoduodenal artery: to the head of the pancreas and the duodenum
• Intestinal branches: to the jejunum and ileum
• Middle colic artery: to the transverse colon
• Right colic artery: to the ascending colon
• Ileocolic artery: to the terminal ileum ,cecum, and ascending colon; it also gives off the Appendicular artery to the appendix!

Question 14

* The Ileocolic artery leads to the terminal ileum ,cecum, and ascending colon. it also gives off the Appendicular artery to the appendix!

Question 15

The embryonic hindgut forms what in the adult?

Answer 15

• Descending colon
• Sigmoid colon
• Rectum andanal canal

Question 16

What are the branches of the inferior mesenteric artery that supply derivatives of the embryonic hindgut, and what do they supply?

Answer 16

• Left colic artery: the descending colon
• Sigmoid arteries: the sigmoid colon
• Superior rectal artery: the rectum and anal canal

Question 17

Branches of the superior and inferior mesenteric arteries anastomose, forming a……………… artery, which runs parallel to the colon. This collateral circulation may prevent infarction of a segment of colon if one of the branches is obstructed or has to be ligated.

Answer 17

marginal

Question 18

Venous drainage from the abdominal GI tract and spleen enters which vein for transport to the liver?

This is unlike blood from the rest of the body. Why?

Answer 18

hepatic portal vein

It does not pass directly toward the superior or inferior vena cava. One consequence is that cancer from the GI tract often metastasizes to the liver!

Question 19

The hepatic portal vein is formed posterior to the neck of the pancreas by the union of what two veins?

Answer 19

• Splenic vein (the inferior mesenteric vein usually drains into the splenic vein)
• Superior mesenteric vein

Question 20

Tributaries of the hepatic portal vein form connections (anastomose) with tributaries of the systemic venous system (venae cavae). These portacaval (portal-systemic) anastomoses may become abnormally dilated if there is resistance to portal blood flow (such as in cirrhosis), increasing pressure within the portal vein. This is called what?

Answer 20

portal hypertension

Question 21

In portal hypertension, portacaval anastomoses that may enlarge include those found where?

Answer 21

• Lower esophagus (as esophageal varices)
• Anal canal (as hemorrhoids)
• Paraumbilical region (as varicose veins radiating outward from the umbilicus, aka caput medusae)

Question 22

……………. may be the source of fatal hemorrhage in portal hypertension, and occurs secondary to cirrhosis of the liver.

Answer 22

Esophageal varices

Question 23

In the condition known as……………….., the subcutaneous veins radiating from around the umbilicus dilate secondary to portal hypertension. The radiating veins reminded an early physician of the snakes on the head of Medusa of Greek mythology

Answer 23

caput medusae

Question 24

When it comes to lymph nodes & vessels associated with the aorta, IVC & iliac vessels, we have:

Answer 24

• pre-aortic nodes
• right and left lateral aortic or lumbar nodes (also called para-aortic nodes)

Question 25

....................nodes (celiac, superior & inferior mesenteric) drain the GI tract and accessory organs. They unite to form the intestinal trunk.

Answer 25

Pre-aortic

Question 26

......................nodes (lumbar) drain body wall, kidneys, adrenal glands & testes or ovaries, and uterus and uterine tubes. They collect to form what?

Answer 26

Para-aortic right and left lumbar trunks

Question 27

The confluence (joining) of all lymph trunks appears as a saccular dilatation called what?

Answer 27

The cisterna chyli

Question 28

The digestive system and other abdominal organs are innervated by nerve fibers that travel along blood vessels to reach the organs. ## Footnote There are autonomic nerve fibers from which ANS nervous system?

Answer 28

BOTH the sympathetic and parasympathetic nervous systems!

Question 29

The sympathetic nervous innervation of abdominal organs consists of................ nerve fibers that reach prevertebral ganglia through splanchnic nerves, and................. nerve fibers from cell bodies in prevertebral ganglia that follow arteries to organs.

Answer 29

preganglionic postganglionic

Question 30

Prevertebral ganglia are located along the abdominal aorta at the origins of the: * Celiac trunk – celiac ganglia * Superior mesenteric artery – superior mesenteric ganglion * Inferior mesenteric artery – inferior mesenteric ganglion * Renal arteries (to the kidneys) – aorticorenal ganglia Here is the picture:

Answer 30

Question 31

Splanchnic nerves that carry preganglionic sympathetic nerve fibers to prevertebral ganglia are the Thoracic splanchnic nerves and Lumbar splanchnic nerves. The thoracic splanchnic nerves are: \* These werent bolded, but know the general idea at least.

Answer 31

–Greater splanchnic nerve (T5-9) –Lesser splanchnic nerve (T10-11) –Least splanchnic nerve (T12)

Question 32

What level are the Lumbar splanchnic nerves located?

Answer 32

L1-2 and occasionally L1-3.

Question 33

Thoracic splanchic (preganglionic) nerves generally supply what?

Answer 33

foregut (celiac trunk) and midgut (superior mesenteric artery) territory. \* Seen in red in the picture!

Question 34

Lumbar (preganglionic) splanchnic nervessupply what?

Answer 34

hindgut (inferior mesenteric artery) territory \* Green on pic!

Question 35

Since the autonomic nerve fibers to visceral organs follow the blood vessels, knowledge of the blood supply gives the source of preganglionic input! Ex: * Celiac ganglia nerve fibers follow celiac trunk branches to foregut derivatives: stomach, proximal duodoenum, liver, gallbladder, pancreas; they also supply the spleen. * Aorticorenalganglia fibers follow renal artery branches to the kidneys and adrenal glands. * Superior mesenteric ganglia fibers follow superior mesenteric artery branches to midgut derivatives: distal duodenum, jejunum and ileum, ascending and transverse colon. Here is the pic from the slide:

Answer 35

Question 36

Inferior mesenteric ganglia nerve fibers follow inferior mesenteric artery branches to hindgut derivatives, which are:

Answer 36

descending colon, sigmoid colon, rectum, and upper anal canal

Question 37

Here is a summary of Splanchnic Nerves picture:

Answer 37

Question 38

As in many other areas of the body, the sympathetic autonomic input tends to produce what in the GI tract?

Answer 38

- vasoconstriction in the vessels of the viscera - reduced glandular secretion - reduced peristalsis \* some of these effects are direct, others are indirect through action on the enteric nervous system.

Question 39

Preganglionic parasympathetic innervation of abdominal organs is from what two sources?

Answer 39

* Vagus nerves (CN X) * Pelvic splanchnic nerves (S2-4)

Question 40

Vagus nerves (CN X) innervate what part of the digestive tract?

Answer 40

foregut and midgut derivatives

Question 41

...................... nerves (S2-4), innervate hindgut derivatives (left colic flexure to anal canal)

Answer 41

Pelvic splanchnic

Question 42

Vagus nerve fibers enter the abdomen through the esophageal hiatus of the diaphragm as anterior and vagal trunks formed from the esophageal plexus. They supply.................... parasympathetic input to ganglion cells located near or within the wall of the visceral structure!

Answer 42

preganglionic

Question 43

Pelvic splanchnic nerves leave the sacral spinal cord through the......... rami of spinal nerves......... and send PREGANGLIONIC parasympathetic fibers to hindgut derivatives.

Answer 43

anterior S2-4

Question 44

In opposition to the sympathetic input, parasympathetic fibers do what?

Answer 44

Increase glandular secretion and increase peristalsis through effects on smooth muscle and the enteric nervous system.

Question 45

Visceral afferent fibers, which accompany................ nerves, carry pain from abdominal viscera to the spinal cord. Visceral pain is stimulated by tissue injury (ex: ischemia), sudden distention, or muscle spasms. Pain from viscera may be referred to other areas of the body that receive somatic innervation (ex: skin) from the same spinal cord segments.

Answer 45

sympathetic

Question 46

Knowing that foregut derivatives (ex: the stomach) receive preganglionic sympathetic innervation from spinal cord segments T5-9 (greater splanchnic nerve), if a patient has referred pain to those dermatomes, it indicates which organs are most likely involved in the pathology causing the pain. Here is the pic from the slides:

Answer 46

Question 47

Irritation of the.............. nerve from inflammation of the diaphragmatic pleura or peritoneum may cause referred pain to the............. shoulder. The pain is referred to the shoulder because afferent fibers of the phrenic nerve (C3,4,5) enter the same spinal cord segments as the supraclavicular nerves (C3,4), which supply cutaneous innervation to the shoulder.

Answer 47

phrenic ipsilateral