It is increasingly recognized that the autonomic nervous system (ANS) is a major contributor in many cardiac arrhythmias. Cardiac ANS can be divided into extrinsic and intrinsic parts according to the course of nerve fibers and localization of ganglia and neuron bodies. Although the role of extrinsic part has historically gained more attention, the intrinsic cardiac ANS may affect cardiac function independently as well as influence the effects of the extrinsic nerves. Catheter based modulation of the intrinsic cardiac ANS is emerging as a novel therapy for management of patients with brady and tachy arrhythmias resulting from hyperactive vagal activation. However, distribution of intrinsic cardiac nerve plexus in the human heart and the functional properties of intrinsic cardiac neural elements remain insufficiently understood. The present review aims to bring the clinical and anatomical elements of the ICANS together, by reviewing neuroanatomical terminologies and physiological functions, in order to guide the clinical electrophysiologist in the catheter lab, and to serve as a reference for further research.