The two chains of sympathetic ganglia extending along the ventrolateral surfaces of the vertebral column from the upper cervical region to the coccyx. Each trunk consists of a series of sympathetic ganglia connected by a nerve cord. These nerve cords are composed largely of nerve fibers associated with the cell bodies within the ganglia. The right and left sympathetic trunks join, at the ventral surface of the coccyx, to form a single ganglion known as the ganglion impar or ganglion of Walther. SEE ganglion impar, ganglion of Walther.