Thoracic cardiac nerves

Thoracic cardiac nerves are branches of the upper four or five thoracic sympathetic ganglia, which provide post-ganglionic sympathetic innervation to the cardiac tissue. The ganglia receive preganglionic sympathetic neurons from the lateral gray horns of the upper thoracic spinal segments. Within the ganglia, the pre-ganglionic neurons synapse with cell bodies of postganglionic sympathetic neurons, which in turn, get distributed to the deep cardiac plexus via the thoracic cardiac nerves.

Please note that apart from the thoracic cardiac nerves, additional postganglionic sympathetic neurons to the cardiac plexuses arrive via the (superior, middle and inferior) cervical cardiac nerves.

The deep cardiac plexus is situated in front of tracheal bifurcation. From here onwards, the sympathetic neurons are conveyed to the heart tissue.