1.2 Abdominal Blood Vessels and Nerves Lecture Flashcards
At what vertebral level does the aorta bifurcate into the common iliac arteries?
L4
What plexus do the pelvic splanchnic nerves travel through?
The inferior hypogastric plexus.
What are the paired visceral arteries that branch from the aorta, and at what vertebral levels do they branch?
Suprarenal (L1).
Renal (L1/L2).
Gonadal (L2).
What do we see clinically if retrograde portal vein blood uses the left gastric artery to return to systemic circulation?
Esophageal varices.
What are the borders of the cystohepatic triangle (triangle of Calot)?
The common hepatic duct (medial).
The cystic duct (lateral).
Inferior border of the liver (superior).
At what point does pain travel with the parasympathetics?
Below the pelvic pain line, where the visceral afferents travel with the pelvic splanchnic nerve.
By definition, what separates internal and external hemorrhoids?
The pectinate line.
How does the vagus nerve enter the abdominal cavity?
It follows the esophagus as the anterior and posterior vagal trunks, and enters through the esophageal hiatus of the diaphragm.
Where are the esophageal varices located, histologically speaking?
In the submucosa of the esophagus.
What is the primary function of sympathetic innervation to the abdomen?
Vasoconstriction and inhibition of peristalsis.
What are the 2 less common configurations for the 3 veins that make up the portal vein?
- The inferior mesenteric vein attaches to the superior mesenteric vein. The superior mesenteric vein and the splenic vein come together to form the portal vein.
- The inferior mesenteric vein, superior mesenteric vein, and splenic vein, all come together to form the portal vein.
What is innervated by the pelvic splanchnic nerves?
The colon and rectum from the splenic flexure to the pectinate line.
What do we see clinically if retrograde circulation from the portal vein opens the umbilical vein to return to systemic circulation?
Caput medusae.
What is the basic path for an abdominal sympathetic nerve from the spinal cord to organ?
Starts at the intermediolateral cell column, passes out the ventral horn and the anterior ramus, goes through the white ramus, and then through the paravertebral ganglia without synapsing. They then continue as the abdominopelvic splanchnic nerves (still presynaptic) and synapse at the prevertebral sympathetic ganglia. They then follow the periarterial plexuses to their target organ.
What structure serves as an anastomosis between the arteries of the midgut and hindgut?
The marginal artery of Drummond.
What is of the name for the opening of the diaphragm through which the inferior vena cava passes?
At what vertebral level is it located?
The caval opening of the diaphragm.
T8
What are the unpaired visceral arteries that branch from the aorta, and at what vertebral levels do they branch?
Celiac (T12).
Superior mesenteric (L1).
Inferior mesenteric (L3).
What are the 4 sympathetic splanchnic nerves innovating the abdomen, and at what vertebral levels do they exit?
Greater splanchnic: T5-T9.
Lesser splanchnic: T10-T11.
Least splanchnic: T12.
Lumbar splanchnic: L1-L2
Where do the right lumbar veins converge and drain?
Into the azygos vein.
Where is a “replaced” right hepatic artery likely to originate?
Superior Mesenteric Artery
What is the significance of the cystohepatic triangle?
In the majority of the population, it is the location of the cystic artery.
Why might the liver still contain a great deal of moving blood, even if the hepatic artery is occluded?
Because 70% of the blood to the liver comes from the portal vein.
What sympathetic ganglia also carry fibers from the vagus nerve?
Celiac.
Superior mesenteric.
Intermesenteric.
Some inferior mesenteric.
What arteries supply the marginal artery of Drummond?
Ileocolic, right colic, middle colic, left colic.
What are the 2 possible routes for the venous return of blood in the rectal venous plexus?
Either through the superior rectal vein and the portal system,
or the middle/inferior rectal veins and the caval (systemic) return system.
What structures are supplied by the short gastric arteries?
The fundus of the stomach.
The superior pole of the spleen.
Is the hypogastric nerve sympathetic or parasympathetic?
The hypogastric nerve is exclusively sympathetic.
What 2 structures can become compressed by the superior mesenteric artery?
What is the name of this syndrome?
Left renal vein, possibly the 3rd part of the duodenum.
Renal vein entrapment syndrome – or “Nutcracker syndrome.”
What are the paired parietal branches of the aorta, and at what vertebral levels do they branch?
Inferior phrenic (T12).
Subcostal (T12).
Lumbar (L1-L4).
In general, which ganglia correspond to the greater, lesser, and least splanchnic, and lumbar nerves?
Greater splanchnic – celiac ganglia.
Lesser and least splanchnic – superior mesenteric ganglia.
Lumbar splanchnic – inferior mesenteric ganglion
Are nerve plexuses of the sympathetic nervous system presynaptic or postsynaptic?
Postsynaptic.
If the entire vena cava was ligated at L5, how could blood still return to the heart?
Ascending lumbar veins.
External iliac veins -> inferior epigastric veins -> superior epigastric veins -> -> superior vena cava.
What is another name for the cystohepatic triangle?
The triangle of Calot.
What do we see clinically if retrograde circulation from the portal vein utilizes the inferior mesenteric vein to return to systemic circulation?
Hemorrhoids.
What 3 major arteries branch into the rectal arteries?
Inferior mesenteric = superior rectal.
Internal iliacs = middle rectal.
Internal pudendal = inferior rectal.
Where do the right and left gonadal veins drain?
The right gonadal vein drains directly into the inferior vena cava.
The left gonadal vein drains into the left renal vein.
Other than the right hepatic artery (most common), what are the 2 most common alternate points of origin for the cystic artery?
Left gastric artery (off of the celiac artery).
Gastroduodenal artery.
Where do the left posterior intercostal veins combine into drain?
Into the hemiazygous vein.
At what level does the aorta pass through the aortic hiatus of the diaphragm?
T12
Does the vagus nerve conveys presynaptic or postsynaptic fibers?
Presynaptic fibers.
Where is the pelvic pain line in terms of G.I.?
The middle of the sigmoid colon.
How can you know if a portion of the pelvic organ will send visceral afferents with the sympathetic or parasympathetic nerves?
Any part of any pelvic organ covered by peritoneum will send that portion of that organ’s visceral afferents with the sympathetic nerves.
What part of the large intestine is at a higher risk for ischemia?
The splenic flexure.
(Because it is the dividing line between the midgut and the hindgut – therefore superior / inferior mesenteric arteries – it is very vulnerable to litigation both proximal and distal to it.)
What are the 2 nerves that make up parasympathetic innervation to the abdomen?
What are the relevant nerve roots?
Vagus nerve: CN X
Pelvic splanchnic nerve: S2-S4
Where does sympathetic innervation to the abdomen originate?
What vertebral segments?
In the intermediolateral cell columns – T5 to L2.
At what vertebral segment does the inferior vena cava begin?
L5
What is the typical case for the arrangements of the 3 vessels that make up the portal vein?
Inferior mesenteric vein attaches to the splenic vein.
Splenic vein and superior mesenteric vein come together to form the portal vein.
What is the course the lumbar splanchnic nerve has to travel to reach the rectum?
Lumbar splanchnic nerve exits at L1 and L2, enters the inferior mesenteric ganglia, enters the abdominal peri-aortic plexus, enters the superior hypogastric plexus, enters the inferior hypogastric plexus, then enters its target location on the rectum.
If the liver is backed up, blood from the portal vein will flow retrograde. What are the 4 options for veins blood can use to get back to systemic circulation?
- Left gastric -> esophageal anastomosis -> azygos vein.
- Inferior mesenteric -> Superior rectal -> middle/inferior rectal -> caval system.
- Reopened umbilical veins -> superior/inferior epigastric veins.
- Colic veins -> (retroperitoneal) lumbar veins -> caval system
What 3 fibers can be present in a sympathetic prevertebral ganglia?
Synapsing sympathetic fibers.
Non-synapsing visceral afferent fibers.
Non-synapsing parasympathetic presynaptic fibers.
What are the 4 prevertebral ganglia for the abdominal sympathetic nerves?
Celiac.
Superior mesenteric.
Inferior mesenteric.
Aorticorenal.
What are the 4 main players of the parasympathetic innervation to the abdomen?
Anterior posterior vagal trunks – the trunks that rotated clockwise around the esophagus.
Pelvic splanchnics from S2-S4.
Abdominal (a.k.a. para-aortic) autonomic plexuses and their extensions, the periarterial plexuses.
Intrinsic (enteric) parasympathetic ganglia. These are the POST-synaptic ganglia that make up the enteric nervous system.
What is the most likely origin for a replaced left hepatic artery?
Left gastric artery.
