Axons of sympathetic preganglionic neurons enter sympathetic trunk ganglia

There are two types of autonomic ganglia: sympathetic and parasympathetic. Sympathetic ganglia are sites of synapses between sympathetic preganglionic and postganglionic neurons.
There are 2 major types of sympathetic ganglia: Sympathetic trunk ganglia (lie in a vertical row on either side of the vertebral column) and prevertebral ganglia (lie anterior to the vertebral column and close to the large abdominal arteries).

After axons of sympathetic preganglionic neurons enter sympathetic trunk ganglia, they may connect with postganglionic neurons in one of 4 ways.
An axon may synapse with postganglionic neurons in the first ganglion it reaches.
An axon may ascend or descend to a higher or lower ganglion before synapsing with postganglionic neurons.
An axon may continue, without synapsing, through the sympathetic trunk ganglion to end at a prevertebral ganglion and synapse with postganglionic neurons.
An axon may also pass, without synapsing, through the sympathetic trunk ganglion and a prevertebral ganglion and then extend to the adrenal medullae.