On each side of the neck, the superior cervical ganglion is an extension of the cervical sympathetic chain. It results from fusion of the upper four cervical spinal nerve ganglia. It is the largest of the ganglia, typically 3cm in length and spindle-shaped.
It lies deep to the carotid sheath at the angle of the mandible. In this position, it is anterior to the lateral mass of the atlas and axis and is separated from them by the prevertebral fascia. The skull base lies superiorly and it is continuous with the middle cervical ganglion inferiorly.
The superior cervical ganglia only receives preganglionic efferent fibres from the thoracic part of the sympathetic trunk. Its branches have a complex distribution - see submenu - to supply blood vessels, glands and pilomotor muscles of the head and neck.