Which nerve gets damaged here if a 59-y/o man complains of numbness in the anterior cervical triangle?

Transverse cervical nerve.

The transverse cervical nerve turns around the posterior border of the sternocleidomastoid and innervates the skin of the anterior cervical triangle. The phrenic nerve, a branch of the cervical plexus, contains motor and sensory fibers but no cutaneous nerve fibers. The greater auricular nerve innervates the skin behind the auricle and on the parotid gland. the supraclavicular nerve innervates the skin over the clavicle and the shoulder. The lesser occipital nerve innervates the scalp behind the auricle.