The sensations of pain arising because of the ischemia of the heart go through the sympathetic fibres to reach the upper 5 thoracic spinal segments (T1-T5) via cervical andthoracic sympathetic ganglia and follow the usual somatosensory pathway to the central nervous system. The pain fibres pass from thoracic ganglia to the spinal nerves via white rami communicantes. The cell bodies of the first order sensory neurons are in the dorsal root ganglia of T1- T5 spinal nerves. For this reason cardiac pain is referred primarily in the area of distribution of these nerves, i.e., pectoral region and medial aspect of the arm and forearm.
Sometimes cardiac pain is referred to the neck and mandible. It’s due to the connection of sympathetic fibres with the cervical nerves.
Pathways For Cardiovascular Reflexes
The afferent fibres from heart subserving the cardiovascular reflexes pass by the parasympathetic fibres of vagal nerves to the reticular formation.