The superior cardiac nerves are branches of the vagus nerve which originate just distal to the inferior vagal ganglion. On each side there are two branches of the superior cardiac nerve, superior and inferior:
- right superior and inferior branches: descend deep to the subclavian artery on the right inferior surface of the anterior trachea to diverge into the deep cardiac plexus
- left superior branch: descends on left side of trachea anterior to oesophagus and deep to the aortic arch to merge with the deep cardiac plexus
- left inferior branch: descends lateral to the trachea before passing over the arch of the aorta and merging with the superficial cardiac plexus in the region of the ligamentum arteriosum
The cardiac nerves carry general visceral parasympathetic motor fibres.