Innervation of Heart

Cardio-Inhibitory Centre (CIC)
  • Dorsal motor nucleus of vagus nerve in Medulla Oblongata
  • On stimulation causes slowing of the heart rate

Parasympathetic Nerve Supply

  • Nerve fibres from the CIC travel through the vagus nerve to the Heart (mainly to the atria, SA node and AV node).
  • Ventricles escape from effects of strong prolonged vagal stimulation - this is called the vagal escape

Vasoconstrictor centre (VCC)

  • No separate cardioaccelerator centre but the VCC produces both vasoconstriction and tachycardia

Sympathetic Nerve Supply

  • From the VCC, fibres descend down in the spinal cord to the lateral horn cells
  • Preganglionic sympathetic fibres from the upper 5 thoracic segments ascend in the sympathetic chain to the superior, middle and inferior cervical ganglia.
  • Post ganglionic nerve fibres descend to the heart (to all parts of the heart muscle)