Blood and Nerve Supply to Abdominal Organs Flashcards
Which branch of the abdominal aorta is the primary supply to foregut derivatives? What are these derivatives?
Celiac trunk
Supplies: Liver and bile ducts Distal esophagus Stomach Duodenum - proximal to common bile duct Pancreas
Which branch of the abdominal aorta is the primary supply to midgut derivatives? What are these derivatives?
Superior mesenteric artery
Supplies: Duodenum - distal to common bile duct Jejunum Ileum Cecum Appendix Ascending colon Transverse colon - proximal 2/3
Which branch of the abdominal aorta is the primary supply to hindgut derivatives? What are these derivatives?
Inferior mesenteric artery
Supplies: Transverse colon - distal 1/3 Descending colon Sigmoid colon Rectum - proximal 1/3
Vertebral level of celiac trunk
T12
Vertebral level of superior mesenteric a.
L1
Vertebral level of inferior mesenteric a.
L3
Vertebral level of bifurcation of abdominal aorta
L4
What is superior mesenteric artery syndrome?
Compression of 3rd part of duodenum by SMA
More common in females; age range 10-39
Results in chronic or intermittent duodenal obstruction, which can be complete or partial
There is an arterial anastomoses between the branches of the SMA and the IMA, predominantly one artery called the ______
What is its significance?
Marginal artery of drummond
Depending on the health of these vessels, and the speed at which obstruction occurs, they could help prevent intestinal ischemia by providing collateral circulation
what is considered to be the ANS master controller?
Hypothalamus
What nerve plexus is considered to be the “second brain” in terms of controlling activity in the stomach, small intestine, and large intestine?
Enteric nervous system (ENS)
Main ENS functions
Controls digestive tract motility
Regulates fluid exchange and local blood flow
Regulates secretions of pancreas and stomach - enzymes and HCl
Regulates hormone production: gastric and intestinal hormones
Mounts defensive reactions against viruses and some bacteria
Autonomic motor (efferent) neurons include:
____ neurons which decrease GI activity by constricting arteries supplying GI tract
_____ neurons which increase GI activity by synapsing with postsynaptic neurons in the ENS, thereby enhancing their activity
Sympathetic postsynaptic
Parasympathetic presynaptic
Visceral sensory (afferent) neurons in the stomach, small intestine, andlarge intestine detect what types of sensations?
Distention (fullness)
Discomfort
Nausea
Pain
Afferent neurons for pain from the proximal GI tract (including organs proximal to splenic flexure) travel to the ______ spinal sensory ganglia and then to spinal cord
Thoracolumbar
Afferent fibers conveying reflex information from proximal GI tract, including organs proximal to splenic flexure, travel with the ____ nerve
Vagus
Afferent fibers for pain and reflex information from distal GI tract (including organs distal to splenic flexure) travel to spinal sensory ganglia S2-S4 via ______ nerves
Pelvic splanchnic
Which spinal segments correspond to greater, lesser, and least splanchnic nerves?
Greater = T5-9
Lesser = T10-11
Least = T12
Which spinal cord segments correspond to lumbar and sacral splanchnic nn?
L1-L2 for both
3 unpaired visceral branches of aorta
Celiac (T12)
Superior mesenteric a. (L1)
Inferior mesenteric a. (L3)
3 paired visceral branches from aorta
Suprarenal a. (L1)
Renal (L1/L2)
Gonadal (L2)
3 paired parietal branches from aorta
Inferior phrenic a. (T12)
Subcostal a. (T12)
Lumbar (L1-4)
Parasympathetic innervation of foregut, midgut, and hindgut
Foregut: vagus n.
Midgut: vagus n.
Hindgut: pelvic splanchnic nn.
Sympathetic innervation of foregut, midgut, and hindgut
Foregut: thoracic splanchnic nn. T5-9
Midgut: thoracic splanchnic nn. T8-12
Hindgut: Lumbar splanchnic nn. L1-2
The aorta enters the aortic hiatus at the diaphragm at ____ vertebral level. It ends at vertebral level ____ by dividing into right and left _____ arteries
T12; L4; common iliac
Is the aorta retroperitoneal or intraperitoneal?
Retroperitoneal
Name the most important anterior relationships of the abdominal aorta from superior to inferior
Autonomic plexi and ganglia Body of pancreas Splenic v. L renal v. Horizontal part of duodenum Coils of small intestine
3 primary branches of celiac trunk
L gastric a.
Splenic a.
Common hepatic a.
Is the L gastric a. intraperitoneal or retroperitoneal? If intraperitoneal, in which omenta, ligament, or mesentery is it located in?
Intraperitoneal
Hepatogastric ligament
Lesser omentum
What branches off the L gastric a.? What does its branch anastomose with?
Esophageal branch - anastomosis with esophageal aa. in the thorax
Is the splenic a. intraperitoneal or retroperitoneal? If intraperitoneal, in which omenta, ligament, or mesentery is it located in?
Both; it is retroperitoneal until it travels through the splenorenal ligament to get to the spleen
What are the 5 branches of the splenic a. and what do they supply?
Posterior gastric a. (Sometimes not present)
Pancreatic branches (supply body and tail of pancreas)
Short gastric aa. (Supply fundus of stomach)
Splenic branches
L gastro-omental a.
Are the short gastric aa. (branches of splenic a.) intraperitoneal or retroperitoneal? If intraperitoneal, in which omenta, ligament, or mesentery is it located in?
Intraperitoneal
Gastrosplenic ligament
Is the L gastro-omental a. (branch of splenic a.) intraperitoneal or retroperitoneal? If intraperitoneal, in which omenta, ligament, or mesentery is it located in?
Intraperitoneal
Gastrocolic ligament
Greater omentum
2 primary branches of common hepatic a.
Proper hepatic a.
Gastroduodenal a.
Is the proper hepatic a. intraperitoneal or retroperitoneal? If intraperitoneal, in which omenta, ligament, or mesentery is it located in?
Intraperitoneal
Hepatoduodenal ligament (with other parts of portal triad - portal v. and common bile duct)
Lesser omentum
Is the gastroduodenal a. intraperitoneal or retroperitoneal? If intraperitoneal, in which omenta, ligament, or mesentery is it located in?
Retroperitoneal
Branches of common hepatic a.
R gastric a.
R and L hepatic branches (cystic a. typically branches off R hepatic a.)
Branches of gastro-duodenal a.
Superior pancreaticoduodenal a. (anterior and posterior)
R gastro-omental a.
Is the R gastro-omental a. (branch of gastroduodenal a.) intraperitoneal or retroperitoneal? If intraperitoneal, in which omenta, ligament, or mesentery is it located in?
Intraperitoneal
Gastrocolic ligament
Greater omentum
Is the superior pancreaticoduodenal a. (anterior and posterior branches of gastroduodenal a.) intraperitoneal or retroperitoneal? If intraperitoneal, in which omenta, ligament, or mesentery is it located in?
Retroperitoneal
The right hepatic a. typically comes off the common hepatic a., what is a common variation of this?
Right hepatic a. may come off superior mesenteric
The L hepatic a. typically comes off the common hepatic, what is a common variation of this?
Left hepatic a. may come off L gastric a.
T/F: proper hepatic a. is usually anterior to portal vein, but a possible variation is that it could be posterior
True
Describe the dual blood supply of the liver
Hepatic portal v. carries relatively oxygenated blood to sustain liver parenchyma (75-80% of liver)
Hepatic a. sustains non-parenchymal structures like the intrahepatic bile ducts (20% of liver)
How does blood flow through the liver relative to bile?
They flow in opposite directions
Blood enters liver from hepatic portal vein and artery toward the central vein
Bile flows from hepatocytes into bile canaliculi, to interlobular biliary ducts, and then to te bile duct in the extrahepatic portal triad
Surgeons often use what anatomical landmark to find the cystic artery?
Cystohepatic triangle of Calot
What 3 structures make up the cystohepatic triangle of Calot?
Common hepatic duct
Cystic duct
Visceral surface of liver
What 3 important arterial anastomoses occur at the stomach and spleen?
L and R gastric aa.
L and R gastro-omental aa.
L gastric + R gastro-omental aa.
An ulceration in the early portion of the duodenum would have the potential of compromising what blood vessel?
Gastroduodenal a.
What vessel(s) supply the head of the pancreas as well as the 2nd and 3rd parts of the duodenum?
Gastroduodenal a. (+branches: anterior and posterior superior pancreaticoduodenal a.)
Superior mesenteric a. (+branches: anterior and posterior inferior pancreaticoduodenal a.)
What vessel(s) supply the body, tail, and neck of the pancreas?
Pancreatic aa. (Which branch from splenic a.)
The anastomoses of what blood vessels represents the transition from supplying the foregut to the midgut?
Anterior superior pancreaticoduodenal a. anastomoses with anterior inferior pancreaticoduodenal a.
[since superior comes from celiac trunk=foregut and inferior comes from SMA=midgut]
note that posterior branches also anastomose
6 Branches of superior mesenteric a.
Inferior pancreaticoduodenal aa.
Ileocolic a. (Supplies cecum and lower part of ascending colon)
Right colic a. (mid to upper part of ascending colon)
Middle colic a. (transverse colon)
Jejunal a.
Ileal a.
Compare/contrast vasa recta and vascular arcades of SMA in the jejunum vs. ileum
Jejunum: long vasa recta, few vascular arcades
Ileum: short vasa recta, many vascular arcades
4 most common variations in SMA
Common trunk for right and middle colic aa.
Common trunk for right and ileocolic aa.
Absent middle colic, replaced by large branch from L colic
Absent right colic a.
Nutcracker syndrome occurs when a loss of mesenteric fat causes the SMA to compress the 3rd part of the duodenum and the ______ vein
L renal
Symptoms of nutcracker syndrome
Proteinuria Hematuria Nausea Vomiting (+bile) L testicular pain in males Varicocele in males (engorged pampiniform plexus d/t backup of blood from L renal v.)
3 major arteries supplying rectum and what they branched from
Superior rectal a. (from IMA)
Middle rectal a. (from internal iliacs)
Inferior rectal a (from internal pudendal a.)
Describe venous drainage of the rectum
Drainage occurs via: Rectal venous plexus Internal pudendal v. Middle rectal v. Superior rectal v.
The rectal venous plexus and superior rectal v. drain into inferior mesenteric v. and eventually into portal v. —> liver
The internal pudendal v. and the middle rectal v. are part of the systemic/caval system. They drain back into common iliac vv. then to the IVC —> heart
Why are interal hemorrhoids not painful, while external hemorrhoids are?
Internal are not painful because they are above the pectinate line
External are below the pectinate line and are innervated by somatic sensory fibers (inferior anal nn.)
Internal hemorrhoids are caused by prolapse of rectal mucosa that contains the normally dilated veins of the _____ venous plexus and typically bleed bright red.
External are due to thromboses or blood clots in the veins of the _____ venous plexus and are covered by skin.
Internal; external
The IVC begins anterior to vertebral level _____, just to the right of midline (right side of aorta). It passes through the caval opening of the diaphragm at ______.
Is it longer or shorter than the aorta?
L5; T8
Longer
Major branches of IVC
R and L common iliac vv.
Lumbar vv.
R and L renal vv.
R and L hepatic vv.
R gonadal v. (L gonadal typically goes to L renal v.)
The ascending lumbar veins anastomose with what venous system?
Azygous
What vein is found anterior to the IVC and posterior to the pancreas?
Portal v.
Is the portal v. intraperitoneal or retroperitoneal? If intraperitoneal, in which omenta, ligament, or mesentery is it located in?
Intraperitoneal
Hepatoduodenal ligament
Lesser omentum
The portal v. is formed from the union of what 2 veins?
Splenic v.
Superior mesenteric v.
The portal vein is usually formed from the union of the splenic v. and superior messenteric v. The inferior mesenteric v. USUALLY empties into the splenic v. What are the 2 most common variations?
Inferior mesenteric v. may drain into superior mesenteric v.
Inferior mesenteric v. may drain directly into hepatic portal v.
Portal-caval anastomoses form when blood flow is somehow obstructed in the liver and the portal system backs up. What are the 4 locations that these anastomoses might form?
Esophageal
Rectal
Paraumbilical
Retroperitoneal
Describe esophageal portal caval anastomoses and the potential clinical implication associated with this
Left gastric v. anastomoses with azygous v.
May cause portal HTN and subsequent esophageal varices
Describe rectal portal caval anastomoses and the potential clinical implication associated with this
Blood backflow through the inferior mesenteric vein into superior rectal vein causes rectal vein to anastomose with middle and/or inferior rectal veins which drain back into caval system
Clinical: hemorrhoids, bleeding
Describe paraumbilical portal caval anastomoses and the potential clinical implication associated with this
Paraumbilical vv. anastomose with epigastric vv. (superior and inferior) which go back to caval system
Clinical: caput medusae
Describe retroperitoneal portal caval anastomoses
Colic veins anastomose with systemic retroperitoneal veins (since descending colon is retroperitoneal)
Esophageal varices can rupture and bleed into the stomach, which may be fatal. Histologically, where would esophageal varices be seen?
Submucosal layer
What nerves contribute to the extrinsic sympathetic innervation of the abdomen, and what are their corresponding spinal levels?
Greater splanchnic (T5-9) Lesser splanchnic (T10-11) Least splanchnic (T12) Lumbar splanchnic (L1-2)
What nerves contribute to the extrinsic parasympathetic innervation of the abdomen?
Vagus n. (CN X)
Plevic splanchnic nn. (S2-4)
Parasympathetic innervation from anterior and posterior vagal trunks travel into the abdomen via the ______hiatus. Pelvic splanchnic nerves travel on ______ plexuses and their extensions, the _____ plexuses
Esophageal; abdominal (para-aortic); periarterial
The vagus nerves convey _______ and ______ fibers (mainly for reflexes) to the abdominal aortic plexuses and the periarterial plexuses, which extend along the branches of the aorta
Presynaptic parasympathetic; visceral afferent
What makes the pelvic splanchnic nerves distinct from other splanchnic nerves?
They have nothing to do with sympathetic trunks
They derive directly from anterior rami of spinal nn. S2-S4
Convey preganglionic presynaptic parasympthatic fibers to the inferior hypogastric (pelvic) plexus
Where are the cell bodies of sympathetic nerves that innervate the abdomen?
Intermediolateral cell column of lateral horn of spinal cord
Trace the path of a sympathetic nerve that innervates the abdomen from the cell body in the intermediolateral column of lateral horn of spinal cord to the abdominopelvic viscera
- Leaves IMC via anterior (ventral) root
- Travels via anterior (ventral) ramus
- Leaves via white rami communicantes
- Passes through paravertebral ganglion as abdominopelvic splanchnic nerve
- Synapses in prevertebral ganglion
- Postsynaptic fibers travel via periarterial plexus
- Synapses at abdominopelvic viscera
Sympathetic abdominopelvic splanchnic nerves synapse in one of the prevertebral ganglia anterior to the aorta prior to travelling via periarterial plexuses to get to target organ. What are the pre-vertebral ganglia?
Celiac ganglion
Superior mesenteric ganglion
Inferior mesenteric ganglion
Aorticorenal ganglion
What is the origin of the lumbar abdominopelvic splanchnic nerves (presynaptic sympathetic)?
Abdominal sympathetic trunk
The greater splanchnic nerves typically synapse with what abdominal prevertebral ganglia prior to traveling to their target organ?
Celiac ganglia
The lesser splanchnic nerves typically synapse with what abdominal prevertebral ganglia prior to traveling to their target organ?
Aorticorenal ganglia
The least splanchnic and lumbar splanchnic nerves typically synapse with what abdominal prevertebral ganglia prior to traveling to their target organ?
Superior and inferior mesenteric ganglia
And intermesenteric/hypogastric plexus
Name the abdominal nerve plexuses
Celiac plexus Superior mesenteric plexus Inferior mesenteric plexus Intermesenteric plexus Superior hypogastric plexus Inferior hypogastric plexus
Describe the celiac nerve plexus.
Where is it located? What nerves contribute to it? Is it sympathetic, parasympathetic, or mixed?
Located superior or on sides of celiac trunk
Predominantly greater splanchnics, but may have some contributions from lesser splanchnics. Some contribution from vagus parasympathetics travelling through but they DO NOT synapse here
Mixed sympathetic and parasympathetic
Describe the superior mesenteric nerve plexus.
Where is it located? What nerves contribute to it? Is it sympathetic, parasympathetic, or mixed?
Located above the superior mesenteric a., often fused with the celiac plexus
Contributions from lesser and least splanchnic nn, and sometimes lumbar splanchnics. Parasympathetics travel through but DO NOT synapse here.
Mixed sympathetic and parasympathetic.
Describe the intermesenteric nerve plexus.
Where is it located? What does it supply? Is it sympathetic, parasympathetic, or mixed?
Located between superior mesenteric a. and inferior mesenteric a.
Sends supply to renal, gonads, and ureters.
Mixed sympathetic and parasympathetic
Describe the superior hypogastric nerve plexus.
Where is it located? What nerves contribute to it? Is it sympathetic, parasympathetic, or mixed?
Located at bifurcation of aorta
Sympathetics only! The sympathetic nerves have already synapsed in inferior, superior, or maybe aorticorenal or celiac ganglia - so they are POSTGANGLIONIC only
R and L hypogastric nn. are the primary sympathetics coming out; they contribute to the inferior hypogastric plexus
Describe the inferior hypogastric nerve plexus.
What nerves contribute to it? Is it sympathetic, parasympathetic, or mixed?
Contributions from pelvic splanchnics (parasympathetics) and hypogastric nn. (sympathetics)
So it is mixed
Describe innervation of the rectum
Sympathetics from: lumbar splanchnics (L1, L2) which synapse in inferior mesenteric ganglia and travel to superior mesenteric plexus to R and L hypogastric nn. to get to inferior hypogastric plexus to get to recutm
Parasympathetics go through pelvic splanchnics to pelvic plexus and anything above pectinate line
[below pectinate line, there is somatic innervation via pudendal n. and branches that supply distal rectum]
Visceral afferent pain fibers travel with sympathetics. What is the exception to this?
They travel with parasympathetics BELOW the pelvic pain line
The pelvic pain line corresponds to inferior limit of peritoneum; for GI tract this is the middle of the sigmoid colon
Visceral reflexes travel with what nerve fibers?
Parasympathetics
