Within the thorax, the inferior cardiac nerves are branches of the right vagus nerve, and to a lesser extent the recurrent laryngeal nerves. They supply general visceral motor parasympathetic fibres to the deep cardiac plexuses.
They are derived from the:
- right vagus nerve: branch off at the level of the right subclavian artery to pass inferiorly on the anterior surface of the trachea posterior to the aortic arch
- right recurrent laryngeal nerve: branch off more superiorly than the fibres direct from the vagus, typically in the mid-section of the trachea; fibres run inferiorly and medially to the anterior surface of the tracheal bifurcation
- left recurrent laryngeal nerve: fibres originate at the same level as the right side but descend more laterally within the tracheo-oesophageal groove to the deep cardiac plexuses