Expansion
Right phrenic runs on the superior vena cava and pericardium; left phrenic crosses the aortic arch
Expansion
Both nerves arise from C3, C4 and C5, descend on scalenus anterior in the neck, and pass in front of the lung root with the pericardiacophrenic vessels.
Right phrenic nerve - the shorter, more vertical course:
- Lateral to the right brachiocephalic vein and superior vena cava
- On the pericardium over the right atrium
- Leaves through the caval opening at T8
Left phrenic nerve - the longer course:
- Crosses the aortic arch, lateral to the vagus
- Passes in front of the left lung root, then over the pericardium of the left ventricle
- Pierces the muscular diaphragm on its own, to the left of the pericardium
Because the left nerve crosses the aortic arch and the aortopulmonary window, it is at risk from tumours and surgery in that region, as is the left recurrent laryngeal nerve, which passes medial to it.