Expansion
Sympathetic from T1 to T5, parasympathetic from the vagus
Expansion
- Sympathetic - preganglionic fibres from T1 to T5, synapsing in the cervical and upper thoracic ganglia. Increase rate, conduction velocity and force of contraction, and dilate the coronary arteries
- Parasympathetic - from the vagus nerve. Slow the rate and reduce atrioventricular conduction, acting mainly on the sinoatrial and atrioventricular nodes
Both sets of fibres converge on the cardiac plexus, lying around the aortic arch and tracheal bifurcation, and divide into superficial and deep parts.
Visceral afferents accompany the sympathetic fibres back to T1 to T4, which is why cardiac pain is referred to the chest, the left arm and the jaw; those somatic territories share the same spinal segments.