Posterior Mediastinum Flashcards
Is it easy to view?
No because anything you image anteriorally will be blocked by theheart
Azygos System of Veins
Runs up both sides of the vertebral column posteriorally. Eventually runs into SVC, provides an alternative pathways used in some diseases
eg) portal hypertension
Where would you find the Azygos Vein? Starts?
Right paravertabral region.
Starts: Where right subcostal vein meets right ascending lumbar vein.
Arches up and over, and drains into the SVC
Hemiazygos vein? Starts?
Opposite to azygos vein, on the left hand side of vertebral column.
Starts: where L subcostal vein meets Left ascending lumbar.
Drains into azygos
Accessory hemiazygos
Also left side, drains into azygos, smallest of the 3
Draw normal azygos drainage and then compare to portal hypertension
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What happens in portal hypertension?
Blood cannot get to the liver from the stomach, the issue is with the portal vein.
As veins to the viscera have no valves, blood can flow either direction. So in portal hypertension blood goes in the opposite direction, lots of little oesophageal veins fill and become engorged. (oesophageal varices)
This is important as it means blood doesn’t hit a ‘roadblock’
Oesoophageal varcies?
Occur portal portal hypertension, veins become tortuous and large. Dangerous as that tissue is not made to be that stretched, and bleeds can occur.
Apart from oesophageal varcies, where else does blood get shunted in portal hypertension?
Rectal varices
Caput medusae
Thoracic Duct
Runs up midline, normal flat and hard to find unless filled with ‘stuff’.
Small, looks like a vein.
Drains ALL lympahtic fluid from abdomen, upper+lower limbs.
Exception: right arm and some of face.
Where does the thoracic duct start, cross and finally drain into?
Starts as cisternae chyli, runs up posterior midline and crosses left at ~T5.
Pops up in left supraclavicular region, where it drains into the azygos sytem where L.subclavian and L.internal jugular meet.
How does the thoracic duct stop venous blood getting through where it drains?
A valve
3 regions where Oesophagus gets compressed?
1) Where aorta arches up and over (in aortic aneurysm)
2) Where the Left main bronchus compresses ( lung cancer or growth)
3) Eosophageal Hiatus (**useful as physiological sphincter)
Nerve Supply to the oesophagus
PS: vagus
Sympathetic: Sympathetic trunks
Arterial/venous supply of oesophagus
Differing art/venous supply at top and bottom
Artery
Sup: aorta
Inf: Left Gastric
Vein
Sup: Azygos system
Inf: Left gastric > portal system
Barium swallow?
Done to diagnose oesophageal issues
Draw extensive arterial system
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Radioradial delay
Take radial pulse on both sides, check they’re the same
Radiofemoral delay
Check radial pulse relatice to femoral
What could cause a radioradial or radiofemoral delay?
Coarctation of the aorta. Usually occurs around where ductus arteriosus is/has closed off. Tissue is similar to to DA but has extended out.
Can still happen anywhere around aorta
Before DA: incompatible
During: iffy
After DA: still get some bloodflow, may not get picked up for ~6weeks
Two ways to get past a coarctation
1) increased bloodflow to anterior intercostals (as the connect to posterior IC)
2) increased bloodflow to superior epigastric as it “buddys” with the inferior epigastric > external iliac > femoral artery
Can occur as arteries don’t have valves
