PREGANGLIONIC NEURONS of the sympathetic system synapse with the POSTGANGLIONIC NEURONS in the SYMPATHETIC GANGLIA. These ganglia together will form sympathetic chain. The sympathetic chains extend down the length of the vertebral column and are divided into four parts:
CERVICAL SYMPATHETIC GANGLIA

🔸Consist of three ganglia: Superior, Middle and Inferior

🔸Superior sends postganglionic fibres to form the internal carotid plexus

🔸Inferior or Stellate ganglion is fused with the first thoracic ganglia

THORACIC SYMPATHETIC GANGLIA

🔸T1-T5 ganglia supply the aortic, cardiac and pulmonary plexus

🔸The last 7 thoracic ganglia form the greater and lesser splanchnic nerves

🔸The lowest splanchnic nerve is formed from the last thoracic ganglia and supplies the renal plexus

LUMBAR PREVERTEBRAL SYMPATHETIC GANGLIA 

🔸Supplies the coeliac plexus

SACRAL SYMPATHETIC GANGLIA (PELVIC)

🔸Contribute to hypogastric and pelvic plexus