There is no direct sympathetic outflow to the head and neck or pelvic region, rather neurones travel up or down from the thoracolumbar sympathetic chain to cervical or sacral ganglia (Fig 1).

The sympathetic outflow to the head and neck is via the superior, middle and inferior cervical ganglia.

The inferior cervical ganglion is often fused with the first thoracic ganglion to form the stellate ganglion at the level of C6, just in front of the neck of the first rib.