Final answer:
The sympathetic innervation to the heart is provided by the postganglionic sympathetic nerve pathway.
Step-by-step explanation:
The sympathetic innervation to the heart is provided by the postganglionic sympathetic nerve pathway. In this pathway, preganglionic neurons originate in the spinal cord and synapse with ganglionic neurons in a sympathetic ganglion.
The postganglionic fibers then project to the heart and release norepinephrine to bind to adrenergic receptors, causing changes in heart rate and function.