AUTONOMIC NERVOUS SYSTEM | ANS OF THORAX | Medicoze

The autonomic nerve supply of the thoracic viscera is via the cardiac, pulmonary and oesophageal plexuses, which each receive sympathetic and parasympathetic contributions. The cardiac plexus lies partly on the ligamentum arteriosum and partly on the tracheal bifurcation. The parts communicate and are a single functional unit. They receive branches from each of the cervical and upper thoracic sympathetic ganglia, and parasympathetic branches from both vagi. Branches of the plexus are distributed with the coronary arteries to the heart and its conducting system. The cardiac plexus also sends branches to the pulmonary plexus. A pulmonary plexus lies around the root of each lung; it receives branches from the upper four cervical ganglia and from both vagi, and supplies the lung substance. The oesophageal plexus is a network surrounding the lower oesophagus. It receives branches from the upper cervical ganglia and both vagi. It supplies the oesophagus, and over the lower oesophagus the right and left vagal trunks emerge from it and descend with the oesophagus to enter the abdomen as the anterior and posterior gastric nerves. Each thoracic sympathetic trunk  lies alongside the vertebral column behind the parietal pleura. It is continuous above with the cervical trunk and below with the lumbar sympathetic trunk. It usually possesses 12 ganglia, each contributed by a thoracic nerve, but half of the first thoracic ganglion is fused to the 7th cervical to form a larger stellate ganglion on the neck of the 1st rib. Each ganglion receives preganglionic fibres in a white ramus communicans from its corresponding spinal nerve, and sends postganglionic fibres back to that nerve as a grey ramus communicans.