Superior/Posterior Mediastinum Flashcards
What section of the aorta is in the superior mediastinum?
Aortic arch
Starts at sternal angle, ends at sternal angle
What are the three branches of the aortic arch?
Brachiocephalic
Left common carotid
Left subclavian
What are the branches of the thoracic aorta?
9 pairs of posterior intercostal arteries
One pair of subcostal arteries - below rib 12
One pair of superior phrenic arteries
Two left bronchial arteries
Two esophageal arteries
What is the level of the aortic hiatus in the diaphragm?
T12
What vessels unite to form the brachiocephalic veins?
Internal jugular veins and subclavian veins
What does the azygous vein drain blood from?
Right thoracic wall via posterior intercostal veins
Left thoracic wall via hemiaxygous and Accessory hemiazygous
Esophague
Lung tissue
Vertebral column/spinal cord
What does the hemiazygous vein drain blood from?
Lower left intercostal spaces
Crosses midline to drain into azygous vein
What does the accessory hemiazygous vein drain blood from?
Middle left intercostal spaces
What is the collateral pathway to the right atrium?
Azygous vein system provides a collateral pathway if the superior/inferior vena cava is blocked
What is superior vena cava syndrome?
Obstruction of superior/inferior vena cava that prevents blood from easily traveling through
Bronchogenic tumor or Liver tumor
What is the thoracic duct?
Main lymph channel body receiving all lymph from below the diaphragm and left side of entire body
Ascends through the aortic hiatus between the azygous vein and thoracic aorta, posterior the the esophagus
What is the cisterna chyli?
Dilated lymph sac in the abdomen that receives lymph from the small intestine
Where does the thoracic duct drain?
Beginning of the left brachiocephalic vein
What is the right lymphatic duct?
Drains upper right side of the body
Receives three lymph ducts: Right sublcavian, right bronchomediastinal, and right jugular
Although these three ducts may drain independently*
Describe the course of the left phrenic nerve
Enters from neck between left subclavian artery and vein
Crosses the arch of the aorta anterior to the left vagus nerve
Courses anterior to the root of the lung and exits by directly piercing the left dome of the diaphragm
Where does the right phrenic nerve exit the middle mediastinum?
Caval opening in the diaphragm with the inferior vena cava
What nerve comes off the left vagus nerve and what is the clinical significance?
Left recurrent layrngeal, which hooks underneath the ligamentum arteriosum and the aortic arch
A physician ligating a patent (open) ductus arteriosus in an infant must not ligate the left recurrent laryngeal nerve
Describe the path of the right vagus nerve
Enters the SM anterior to the right subclavian artery
Descends lateral to the trachea
Gives off right recurrent laryngeal
Where are the left and right vagal trunks located?
Left - anterior side of the esophagus
Right - posterior side of the esophagus
Both pass through the diaphragm with the esophagus
How are the branches of the sympathetic ganglia divided?
Upper five - sympathetics which supply vaious thoracic viscera (postganglionic)
Lower five - form three thoracic splanchnic nerves (preganglionic)
What are the greater splanchnic nerves?
Arises from fifth to ninth or tenth thoracic ganglia
Descend across the vertebral bodies medially, and passes into the abdomen through the crus of the diaphragm, ends in the celiac ganglion
What are the lesser splanchnic nerves
Aris from 9th and 10th or 10th and 11th thoracic ganglia
Descends across the vertebral bodies medially through the crus of the diaphragm
Ends in the aorticorenal ganglion
What are the least splanchnic nerves?
Arise from 12th thoracic ganglion
Descends through the crus to end in the renal plexus
What is the location and blood supply of the the thymus?
Immediately posterior to the manubrium
Branches of internal thoracic artery and inferior thyroid artery
