On each side, the middle cervical ganglion is an extension of the thoracic sympathetic chain. It is formed from the fusion of the fifth and sixth cervical spinal nerve ganglia. It is relatively small compared to the other cervical ganglia.
It is sited lateral to the body of the sixth cervical vertebra but medial to its carotid tubercle. It is sited anterior to the prevertebral fascia and the vertebral artery. It is connected to the superior cervical ganglion superiorly and the inferior or stellate ganglion inferiorly. The connection to the latter may be via a group of fibres termed the ansa subclavia.
The middle cervical ganglia only receive efferent fibres ascending from the ipsilateral sympathetic trunks. Their efferent branches have a complex distribution - see submenu.