Lecture 9: Blood and Nerve Supply Flashcards
What vertebral level does aorta enter the abdomen and where does it divide?
- Enters via aortic hiatus of diaphragm at T12
- Ends at L4 by dividing into right and left common iliacs
What are the unpaired visceral branches of the aorta, their spinal levels, and which embryologic region does each branch supply?
- Celiac (T12) - foregut
- Superior mesenteric (L1) - midgut
- Inferior mesenteric (L3) - hindgut
What are the paired visceral branches of the aorta and spinal levels?
- Suprarenal (L1)
- Renal (L1/L2)
- Gonadal (L2)
What are the paired parietal branches off the aorta and vertebral levels?
- Inferior phrenic (T12)
- Subcostal (T12)
- Lumbar (L1-L4)
What are the foregut derivatives, major artery supply, innervation, and referred pain region?
Organs: Esophagus, stomach, liver and pancreas, biliary apparatus, and proximal duodenum
Innervation: Greater splanchnic (T5-T9)
Artery: Celiac
Referred pain: Epigastrium
What are the midgut derivatives, major artery supply, innervation, and referred pain region?
Organs: Small intestine, cecum and appendix, ascending colon, right 1/2 of transverse colon
Innervation: thoracic splanchnic (T8-12)
Artery: Superior mesenteric
Referred pain: Umbilical region
What are the hindgut derivatives, major artery supply, innervation, and referred pain region?
Organs: Left 1/2 transverse colon, descending colon, sigmoid colon, rectum, superior anal canal
Innervation: Lumbar splanchnics (L1-L2)
Artery: Inferior mesenteric artery
Referred pain: Hypogastrium
What are the 3 branches off the celiac trunk?
1) Left gastric a
2) Splenic a
3) Common hepatic a
What is the blood supply to the liver off the celiac trunk?
Common Hepatic artery –> Proper hepatic artery branches into R. and L. Hepatic arteries. The cystic artery will usually branch off the right hepatic artery.
What are 2 vascular variations of the hepatic arteries?
1) Accessory or replaced right hepatic artery coming from SMA
2) Accessory or replaced left hepatic artery coming from left gastric a
What are the relationships of the right hepatic artery to the portal vein?
- Commonly right hepatic artery is anterior to portal vein
- Sometimes, rarely, can be posterior to portal vein
Explain the dual blood supply to the liver and what each supplies?
1) Hepatic portal vein (75-80%) - sustains liver parenchyma
2) Hepatic artery (20-25%) - sustains non-parenchymal structures (intrahepatic bile ducts)
What is the cystohepatic triangle (of Calot) made up of; significance?
- Cystic duct, common hepatic duct, and visceral surface of liver
- Where the Cystic artery is often found
What arteries anastomose at the lesser curvature of the stomach?
Left and right gastric arteries
What arteries anastamose at the greater curvature of the stomach?
Right and left gastro-omental arteries
What are the anastomses of the stomach formed by the left gastric artery?
Left gastric –> Right gastro-omental
Left gastric –> Left gastro-omental
Left gastric –> Right Gastric
Which artery supplying the stomach can be compromised with a posterior rupture from a peptice ulcer?
Gastroduodenal a.
What branches does the gastroduodenal artey give off to supply what part of pancreas and duodenum?
- Anterior and posterior superior pancreaticoduodenal arteries
- Supplies head of pancreas and 1st/2nd part of duodenum
What branches does the SMA give off to supply what part of pancreas and duodenum?
- Anterior and posterior inferior pancreaticoduodenal arteries.
- Supplies 3rd and 4th part of the duodenum
What arteries do the major blood supply for the tail, body, and neck of the pancreas and where do they arise from?
1) Dorsal pancreatic artery
2) Greater pancreatic artery
*Arise from the Splenic a.
What marks the transition from foregut to midgut?
The anastomosis between anterior and posterior superior pancreaticoduodenals w/ the anterior and posterior inferior pancreaticoduodenals.
Describe what the SMA does as it enters the middle of the colon, what vertebral level, what are its branches?
- Starts retroperitoneal, but then descends into the mesentery, supplies midgut at level of L1.
- Branches into:
- Jejunal as.
- Ileal as.
- Middle Colic - transverse colon
- Right Colic - superior part of ascending colon
- Ileocolic - lower part of ascending colon
- Appendicular - appendix
We will need to distinguish the Jejunal arteries from the Ileal arteies, what are the key features that will help us differentiate between the two?
Jejunum = long vasa recta w/ few arcades
Ileum = short vasa recta w/ many arcades
What are two of the common variation in the SMA colic arteries?
1) Absent middle colic replaced by large branch from left colic
2) Absent right colic artery
What are the Sx’s of renal vein entrapment syndrome?
- Blood and protein in urine
- Flank pain
- Nausea and bilious vomiting
- Left testicular pain
- Left sided varicocele
What are the branches of the IMA and what spinal level?
- L3
- Left Colic (ascending and descending branch)
- Sigmoid arteries
- Superior rectal as.
What is the anastomotic connection between midgut and hindgut in the colon?
- Middle colic from the SMA anastomses w/ left colic from the IMA = Marginal artery (of Drummond)
Which arteries form the Marginal artery (of Drummond)?
Ileocolic (SMA), Right colic (SMA), Middle colic (SMA), left colic (IMA), and sigmoid (IMA)
What are the 3 rectal arteries and their origins?
1) Superior rectal (from IMA)
2) Middle rectal (from internal iliacs)
3) Inferior rectal (from internal pudendal)
Describe the path of venous drainage from rectal venous plexus onward; what is this system called?
Rectal venous plexus –> Internal pudendal vein —> common iliacs —> IVC —> heart
* The Cavle system*
Where does the middle and inferior rectal veins drain into?
- Inferior –> Internal pudendal –> common iliacs –> IVC
- Middle –> common iliacs –> IVC
Where does the superior rectal vein drain?
Into the Inferior Mesenteric Vein –> Portal Vein –> Liver
Describe internal hemorrhoids
- Prolapse of rectal mucosa that contains normally dilated veins of the internal venous plexus
- Bleeding is bright red
- NOT painful because are ABOVE pectinate line
Describe external hemorrhoids
- Thromboses or blood clots in veins of the external venous plexus
- Covered by skin
- Painful because they are below the pectinate line and are innervated by somatic sensory nerve fiber (inferior anal nerves)
Describe the anatomical postion of the IVC in the abdomen
- Begins anterior to L5, 2.5cm to the right of midline, right side of aorta
- Passes through the caval opening of diaphragm at T8
IVC drains blood from which structures in the abdomen?
- Lower limbs and paired visceral structures i.e., kidneys and suprarenal glands
- Does NOT drain the digestive tube
How do the left and right testicular veins differ?
- Left testicular drains into left renal –> IVC
- Right testicular drains directly into IVC
What is an anastomotic connection of the IVC?
Ascending lumbar vein anastomoses w/ azygous system (hemiazgous vein in thorax)
What is the anatomical position/relationship of the Portal Vein; passes thru which ligament?
- Anterior to the IVC
- Posterior to the Pancreas
- Found in hepatoduodenal lig.
What 3 veins converge to form portal vein, and what’s the classical route?
- Superior Mesenteric Vein
- Inferior Mesenteric Vein
- Splenic vein
*Typically the IMV drains into the Splenic V, which then converges with the SMV to make the Portal Vein
What is the role of the Portal vein?
Drains the digestive tube
What are the 4 Portal-Caval Anastomoses?
1) Esophageal - left gastic vein –> Esophageal (azygous system)
2) Rectal - Superior rectal –> middle or inferior rectal Vs.
3) Paraumbilical - Paraumbilical V –> Epigastric V.
4) Retroperitoneal - Colic V –> Systemic retroperitoneal vs.
What are the 3 conditions that can arise from Portal HTN?
1) Esophageal varices
2) Rectal - hemorrhoids
3) Paraumbilical - Caput Medusae
Describe the type of fibers that the Vagus nerve conveys, supplies what ‘derm structures, and stops where?
- Pre-synaptic parasympathetic and visceral afferent fibers to the abdominal aortic plexuses and the periarterial plexus
- Supplies foregut and midgut structures, stops at the left colic (splenic) flexure
How are the pelvic splanchnic nerves distinct from other splanchnic nerves; supply which ‘derm?
- Have NOTHING to do w/ the sympathetic trunks
- Convey PREsynaptic PARAsympathetic fibers to the inferior hypogastric (pelvic) plexus
- Supply hindgut endoderm
Describe the path of the cell bodies for sympthathetic innervation
- Pre-synaptic cell body leaves lateral horn via ventral root and joins mixed spinal nerves
- Leaves ventral ramus via white rami communicantes and passes thru para-vertebral ganglia
- Synapse on the pre-vertebral ganglia of sympathetic chain
- Post-synaptic cell now travels on BV’s via periarterial plexus to target organ
What passes through the Celiac ganglion/plexus?
- Pre-dominantly Greater Splanchnic (sympathetic), but Vagus (parasympathetic) travels through it
What sympathetic nerve synapses on the aorticorenal ganglion?
- Least splanchnic (T12)
The superior mesenteric plexus gets contributions from?
- Celiac plexus, lesser, least, and sometimes lumbar
- Parasympathetics travel through here
What travels through the intermesenteric plexus and supplies what?
- Mix of sympathetic and parasympathetic
- Supplies kidneys, gonads, and ureters
What travels through the superior hypogastric plexus?
- Purely post-synaptic sympathetics
The inferior mesenteric ganglion/plexus gets contributions from?
- Intermesenteric plexus
- Lumbar splanchnics
The right and left hypogastric nerve is made up of what kind of autonomic innervation and contributes to?
- Post-ganglionic sympathetics
- Contributes sympathetics to the inferior hypogastric plexus
What does the inferior hypogastric plexus innervate and what kind of nerves does it contain?
- Sympathetics from the R and L hypogastric nerve
- Pelvic splanchnics (para-sympathetics) travel through
- Supplies a lot of pelvic organs
Where do parasympathetics synapse?
Travel through ganglion to wall of the organ where they synapse in the Myenteric plexus of Auerbach or Submucosal plexus
Describe sympathetic innervation of the rectum by the lumbar splanchnics
- Lumbar splanchnics synapse at the IMG, which send post-synaptic fibers to the superior and inferior hypogastric plexuses
- Innervate anything above pectinate line
Describe parasympathetic innervation of the rectum.
- Pelvic splanchnics go through the inferior hypogastric plexus and innervate anything above pectinate line
How is the rectum innervated below the pectinate line?
- Somatic innervation via the pudenal nerve
Pain travels with which visceral afferents and what’s the exception?
- Travels w/ sympathetics
- EXCEPTION: Travels w/ parasympathetics below the pelvic pain line
What is the pelvic pain line and its significance?
- Corresponds to the middle of the sigmoid colon
- Anything from middle to superiorly, pain will be carried by sympathetics (lumbar plexus)
- Anything from middle to inferior, pain will be carried by parasympathetics (pelvic splanchnics)
Visceral reflexes travel w/ what part of autonomics?
Parasympathetics
Which vessels travel through the hepatoduodenal lig?
- Portal triad
- Right Gastric a.
- Proper Hepatic a.
- Portal V.
Which vessels travel through the splenorenal lig?
Splenic a and v
Which ligament does the left gastric artery travel through?
Hepatogastric lig
Which ligament do the short gastric arteries travel through?
- Gastrosplenic lig
Which ligament do the left and right gastro-omentals travels through?
Gastrocolic lig.
