As a result of fusion, on each side there are three interconnected cervical sympathetic ganglia:
- superior cervical ganglion; there are no ganglia more superior
- middle cervical ganglion
- inferior cervical ganglion; the inferior ganglion may be fused with the first thoracic ganglion to form the stellate ganglion
The cervical ganglia are an extension of the thoracic paravertebral sympathetic trunk lying inferiorly. They function as part of the circuit to distribute sympathetic fibres to the head and neck; they are a necessary relay as the sympathetic outflow from the spinal cord, via the anterior roots, emerges no more superiorly than the level of T1. Thus, the cervical ganglia are not associated with white rami communicantes carrying preganglionic fibres - preganglionic fibres ascend from the thoracic part of the trunk.
The chain enters the neck closely apposed to the anterior surface of the neck of the first rib. It ascends anterior to the prevertebral fascia but posterior to the carotid sheath. Laterally is the ipsilateral vertebral artery.
Interruption of the cervical sympathetic chain is one cause of Horner's syndrome.