The Superior Mediastinum Flashcards
What is the mediastinum?
Central compartment of thorax, located between pleural sacs
The superior mediastinum extends upwards from the________
sternal angle (level of T4 vertebrae)
Where does the superior mediastinum terminate?
superior thoracic aperture
The inferior mediastinum extends downwards from the _________
sternal angle (level of T4 vertebrae)
Where does the inferior mediastinum terminate?
diaphragm
Which three major branches of the aortic arch arise in the superior mediastinum?
brachiocephalic artery, left common carotid artery, left subclavian artery
What does the brachiocephalic artery supply?
right side of head and neck, right upper limb
what does the left common carotid artery supply?
left side of head and neck
what does the left subclavian artery supply?
left upper limb
Which tributaries of the superior vena cava are found in the superior mediastinum?
brachiocephalic veins(left and right), left superior intercostal vein, supreme intercostal vein, azygous vein
What vessels drain into the left superior intercostal vein?
left 2nd and 3rd intercostal veins
Which vein drains into the supreme intercostal vein?
the vein from the first intercostal space
Where does the azygous vein receive blood from?
the right posterior intercostal veins. The left intercostal veins drain first into the hemiazygos and accessory hemiazygos veins before joining the azygos vein around T7-T9.
Which major nerves are located in the superior mediastinum?
Left and right vagus nerve, phrenic nerve, cardiac nerves, sympathetic trunk
What is the path of the left vagus nerve?
It enters the superior mediastinum between the left common carotid and the left subclavian arteries. It descends anteriorly to the aortic arch, before travelling posterior to the left bronchus.
What is the path of the right vagus nerve?
runs parallel to the trachea and passes posteriorly to the superior vena cava and the right primary bronchus
Which nerve arises from the left vagus nerve and loops under the aortic arch?
left recurrent laryngeal nerve
Where does the phrenic nerve enter the superior mediastinum?
anterior surface of anterior scalene muscle, lateral to great vessels. then descend anteriorly
Which nerve forms superficial and deep cardiac plexuses in superior mediastinum?
cardiac nerves
Where does the superior plexus sit?
between the aortic arch and right pulmonary vein
Where does the inferior plexus sit?
on the surface of the trachea at the point of bifurcation
What is the route of the sympathetic trunk?
runs bilaterally to the vertebral bodies along the entire length of the vertebral column
What other structures are found in the superior mediastinum?
thymus, trachea, oesophagus, thoracic duct, muscles
