The cervical plexus has both superficial and deep components. The superficial plexus contains cutaneous branches from the ventral rami of C2-4 providing innervation from the posterior cranium to the shoulder via the lesser occipital, greater auricular, transverse cervical, and supraclavicular nerves. The superficial plexus can be very easily blocked and utilized as supplementary analgesia for carotid endarterectomy (CEA) and other neck surgeries. As the sole anesthetic, one study even found equivalent benefits of the superficial-cervical-plexus block compared to combined superficial- and
deep-cervical-plexus blocks for CEA. It can also be used to ensure cutaneous coverage of the shoulder following interscalene block.

Infiltration of local anesthetic deep to the posterior border of the sternocleidomastoid muscle will block the superficial cervical plexus. At the midpoint of the muscle’s posterior border, a 22G 4-cm needle is inserted just below to the muscle and 5 mL of local anesthetic is injected. The needle is then redirected cephalad and caudad along the muscle border, with a total of 10 mL injected along these paths. The external jugular vein often overlies this area and should be avoided. When this block is properly performed, deeper structures should not be affected; however, one should be aware of the proximity of the phrenic nerve, the internal jugular vein, and the carotid artery if the needle is inserted too deeply.