(9) Abdominal Cavity 2

hepatic portal vein

Drains all blood from digestive organs to the liver for filtration. Posterior to hepatic artery proper & common bile duct in portal triad. Formed when the splenic vein joins the superior mesenteric vein.

splenic vein

drains the spleen, pancreas, and stomach. runs just posterior to pancreas & just inferior to splenic artery. joins with superior mesenteric vein to form hepatic portal vein.

superior mesenteric vein

drains small intestines and ascending colon. joins with splenic vein to form hepatic portal vein.

inferior mesenteric vein

drains most of large intestine into either the splenic vein or superior mesenteric vein.

hepatic veins

drain blood from the liver to the inferior vena cava after it has been filtered. Not directly attached to hepatic portal vein.

left gastric vein

Drains the lesser curvature of the left side of the stomach directly into the hepatic portal vein. Receives blood drained by esophageal branch.

esophageal branch

drains inferior esophagus into left gastric vein

right gastric vein

drains blood from the lesser curvature of the right side of the stomach into the hepatic portal vein

middle colic vein

Drains blood from the transverse colon into the superior mesenteric vein

right colic vein

Drains blood from the ascending colon into the superior mesenteric vein

ileocolic vein

drains blood from the ileum & cecum into the superior mesenteric vein

intestinal veins

Drain blood from the jejunum & ileum into the superior mesenteric vein

left colic vein

Drains blood from the descending colon into the inferior mesenteric vein. Located much higher in abdomen than left colic artery.

sigmoid vein

Drains blood from the sigmoid colon into the inferior mesenteric vein

superior rectal vein

Drains blood from the upper rectum into the inferior mesenteric vein

hepatic portal system vs systemic (caval) system

-The primary vessel of the hepatic portal system is the hepatic portal vein, which drains the gut & its outgrowths into the liver for filtration. There are no valves.

-The primary vessel of the systemic system is the IVC, which drains the remainder of the abdominal cavity organs. There are valves.

Portal-Systemic Anastomoses

Connections between vessels in the portal and systemic venous systems.

Gastroesophageal anastomosis

connection between the left gastric vein & the esophageal veins

Anorectal Anastomosis

connection between the superior rectal vein & the middle & inferior rectal veins

Paraumbilical Anastomosis

connection between the paraumbilical veins & the epigastric veins

retroperitoneal anastomosis

connection between colic veins & retroperitoneal lumbar veins

portal-systemic varices

Occur when pressure in portal system exceeds systemic pressure. blood leaks out of anastomosis cause swelling/stretch of vessels.

esophageal varices

enlarged and swollen veins at the lower end of the esophagus at the Gastroesophageal Anastomosis. If they rupture, mortality is 50% within 6 weeks.

Rectal varices

swollen, distended veins in anal canal at the anorectal anastomosis.

caput medusae

enlargement of veins of anterior abdominal wall at the paraumbilical anastomosis. visible through superficial

skin. Common cause cirrhosis of liver.

mesentery

double layer of peritoneum that suspends organs. creates pathway for vessels from abdomen to organ

the gut of an early embryo shows

GI organs symmetrical in midline

ventral mesentery

becomes lesser omentum and falciform ligament during fetal development

dorsal mesentery

connects developing gut tube to anterior surface of aorta. becomes greater omentum & every other named mesentary besides lesser omentum & falciform ligament during fetal development. hangs off greater curvature overtop midgut. has an anterior sheath & a posterior sheath.

Rotation of the gut during development

stomach rotates 90 degrees clockwise, while midgut rotates counterclockwise. results in left side of the abdominal cavity being shifted forward, so the left vagus nerve becomes the anterior vasal trunk & the right vagus nerve becomes the posterior vasal trunk.

lesser sac

opening posterior to stomach that was pinched behind stomach during development. contents of stomach leak here in cases of severe ulceration.

Omental foramen (epiploic foramen)

only connection from lesser sac to rest of abdomen

transverse mesocolon

mesentery that suspends the transverse colon. as development progresses, it fuses with the posterior sheath of the dorsal mesentery & the transverse colon swings forward.

greater omentum consists of

gastrocolic ligament & apron of greater omentum

gastrocolic ligament

Part of the greater omentum that connects the stomach to the transverse colon.

apron of the greater omentum

Part of the greater omentum that is a remnant of dorsal mesentery

retroperitoneal

located behind the peritoneum & attached to the posterior abdominal wall

Mesenteric ("intraperitoneal) Structure

an abdominal structure suspended by a mesentery

-stomach, 1st part of duodenum, jejenum, ileum, cecum, appendix, transverse colon, sigmoid colon, tip of tail of pancreas, liver, gallbladder, spleen

Primarily Retroperitoneal Structure

an abdominal structure that has never been suspended by a mesentery, even earlier in development.

-descending aorta, IVC, lumbar sympathetic chain, kidneys, ureters, suprarenal glands, gonadal vessels

Secondarily Retroperitoneal Structure

An abdominal structure that was suspended by a mesentery earlier in development but became attached to posterior abdominal wall. Always a derivative of the gut tube.

-2nd/3rd part of duodenum, pancreas, ascending colon, descending colon

effects of sympathetic nervous system on GI organs

digestive processes are down-regulated; decreased peristalsis, secretion, and blood flow

effects of parasympathetic nervous system on GI organs

digestive processes are up-regulated; increased peristalsis, secretion, and blood flow, promotion of defecation

sympathetic preganglionic cell bodies for abdominal cavity

T5-L2 levels of IML column/lateral horn

sympathetic preganglionic axons for abdominal cavity

do not synapse in sympathetic chain, instead pass through splanchnic nerves

greater splanchnic nerve

T5-T9

lesser splanchnic nerve

T10-T11

least splanchnic nerve

T12

lumbar splanchnic nerves

L1-L5 (*bc some preganglionics from L1 and L2 also descend to L3-5 before exiting chain)

sympathetic Postganglionic Cell bodies for abdominal cavity

found in ganglia surrounding abdominal aorta (subdiaphragmatic ganglia) & in major ganglia associated with roots of celiac trunk, SMA, & IMA

sympathetic postganglionic axons for abdominal cavity

distribute to organs by following arteries ("periarterial plexuses")

proximal meaning in abdominal cavity

toward esophagus

distal meaning in abdominal cavity

toward rectum

the 5-4-3 rule for sympathetic innervation to abdominal organs

there are 5 levels of sympathetic outflow to foregut organs (T5-T9), 4 levels of sympathetic outflow to midgut organs (T9-T12), & 3 levels of sympathetic outflow to hindgut organs (T12-L2)

*the more proximal an organ, the higher the spinal cord levels that innervate it

parasympathetic preganglionic cell bodies for abdominal cavity

located in the vagus nerve for foregut & midgut organs, located in S2/3-S4/5 & travel via pelvic splanchnic nerves for hindgut organs.

parasympathetic postganglionic cell bodies for abdominal cavity

found in walls of target organs

referred pain of abdominal organs

T5-L2 dermatomes. Can be sharp & well-localized, but can also come from somatic pain in nearby parietal peritoneum innervated by nerves of body wall or diaphragm

pathway of lymphatic drainage of abdominal cavity

preaortic nodes -> intestinal trunk -> cisterna chyli -> thoracic duct