Superior cervical ganglion. A very large superior cervical ganglion in the area of cervical vertebrae CI and CII marks the superior extent of the sympathetic trunk (Figs. 8.193 and 8.194). Its branches pass to: the internal carotid and external carotid arteries, forming plexuses around these vessels, cervical spinal nerves C1 to C4 through gray rami communicantes, the pharynx, and the heart as superior cardiac nerves.