Which is thickened nerve shown here :

The greater auricular nerve is a cutaneous branch of the cervical plexus that innervates the skin of the auricle as well as skin over the parotid gland and mastoid process. The greater auricular nerve also supplies branches that innervate the deep layer of the parotid fascia. Origin The greater auricular nerve arises from the ventral rami of C2 and C3 spinal nerves , although it receives considerably more fibres from C2. Course The greater auricular nerve emerges along the posterior aspect of the sternocleidomastoid muscle at the punctum nervosum (Erb point) and ascends veically across the oblique sternocleidomastoid muscle. When the greater auricular nerve approaches the inferior pole of the parotid gland it divides into anterior and posterior terminal branches. REF : HAZARIKA 4TH ED