M103 T1 L2 Flashcards
What is the division between the superior and inferior mediastinum?
the transverse thoracic plane
What are the boundaries of the superior mediastinum?
superiorly - the superior thoracic aperture / inlet inferiorly - the sternal angle anteriorly - the manubrium posteriorly - T1 to T4/5 laterally - mediastinal pleura
What are the contents of the superior mediastinum?
trachea & oesophagus
part of the thymus gland & the thoracic duct
phrenic and vagus nerves
arteries - branch of the aorta and branches
veins - brachiocephalic veins, superior vena cava
Why don’t we see the thymus gland in an adult corpse in dissection?
after puberty, the thymus gland atrophies and is replaced by fat
After T-lymphocytes are matured in the thymus gland, where do they go?
they drain into the surrounding area, from the parasternal, brachiocephalic and tracheobronchial nodes
What supplies the thymus?
the internal thoracic artery
What are the arteries in the superior mediastinum?
the arch of the aorta and its 3 branches
What are the three branches of the aortic arch? (BCS)
Brachiocephalic trunk
left Common Carotid artery
left Subclavian artery
What are the branches of the aorta?
ascending aorta
descending aorta
arch of aorta
What branches off the descending aorta?
posterior intercostal arteries
bronchial arteries
lumbar arteries
What is the function of the Ductus Arteriosus in embryology and in adults?
Important in fetal circulation allowing blood to bypass the immature lungs.
Closes at birth and remains in the adult as a ligamentous structure
What are the three features of the trachea?
Tube C-shaped cartilage rings
Trachealis muscle runs posteriorly
Runs from Larynx to Bronchi
From where does the phrenic nerve originate?
the anterior rami of spinal nerves C3-C5
What does the phrenic nerve supply?
the diaphragm
posterior phrenic nerve - supplies the back
anterior phrenic nerve - supplies everything else
Where does the phrenic nerve originate from?
the anterior rami of C3-5
Why is it hard to observe the phrenic nerve as it passes along the pericardium in a cadever?
it’s often fused with the pericardium and it’s hard to differentiate
Where does the vagus nerve enter the superior mediastinum in respect to the phrenic nerve?
medial to the phrenic nerve
What is unusual about how the vagus nerve travels and why is it like this?
it’s coming from the brain all the way down the neck into the thorax, then back up all the way up the neck and to the larynx
this happens because of the way the embryo develops with the aorta arches
Where does the vagus nerve supply (parasympathetically) and by which plexi? (COP)
most of the thorax via cardiac, oesophageal and pulmonary plexi