Cardiac and pulmonary sympathetic nerves
Postganglionic · Pregang. T1–T4 β1 heart NA
Postganglionic fibres from the three cervical ganglia (superior, middle, inferior cervical cardiac nerves) and from the T1–T4/5 thoracic ganglia form the cardiac plexus; pulmonary branches from T2–T5 join the pulmonary plexus. Their preganglionic neurones are the cardiac accelerator segments T1–T4.
Traced from the start
Detail
- Heart
- SA node, AV node, atrial and ventricular muscle, coronary vessels — noradrenaline on β1 (some β2)
- Afferents sharing the route
- Cardiac pain fibres travel back through the cardiac plexus to T1–T4/5 — hence referral to the chest wall and medial arm
- Left versus right
- Right-sided nerves predominantly affect SA node rate; left-sided nerves affect AV conduction and ventricular contractility
When it goes wrong
Myocardial ischaemia stimulates afferents that share T1–T5 sympathetic routes
Pain referred to the retrosternal chest, left arm (T1 dermatome, medial arm) and jaw rather than felt over the heart
Refractory ventricular arrhythmia or long QT syndrome
Left stellate ganglion block or cardiac sympathetic denervation reduces arrhythmia burden by removing β1 drive to the ventricle
Practise this structure
1 question in the bank tagged Autonomic Control.