Secretomotor supply of parotid comes from:
The parotid gland is supplied by the parasympathetic, sympathetic and sensory fibres:

Parasympathetic (secretomotor) supply: It  is  provided through auriculotemporal nerve.  The preganglionic fibres arise from the inferior salivatory nucleus in the medulla and pass successively through glossopharyngeal nerve, tympanic branch of glossopharyngeal (Jacobson’s nerve), tympanic plexus and lesser petrosal nerve to relay into otic ganglion. Postganglionic fibres arise from the cells of the ganglion and pass through the auriculotemporal nerve to supply the parotid gland. The stimulation of parasympathetic supply produces watery secretion.
Sympathetic supply: It is derived from sympathetic plexus around external carotid artery formed by postganglionic fibres derived from superior cervical sympathetic ganglion. The preganglionic sympathetic fibres arise from the lateral horn of T1 spinal segment. The sympathetic fibres are vasomotor and their stimulation produces thick sticky secretion.
Sensory supply: It is derived from:

(b)  Auriculotemporal nerve.
Great auricular nerve (C2 and C3). The C2 fibres are sensory to the parotid fascia.
Key Concept:Postganglionic fibres arise from the cells of otic ganglion and pass through the auriculotemporal nerve to supply the parotid gland. The stimulation of parasympathetic supply produces watery secretion. The sympathetic fibres are vasomotor and their stimulation produces thick sticky secretion.
Reference: TEXTBOOK OF ANATOMY HEAD, NECK AND Brain, Volume III, second edition page no 116
Greater Petrosal nerve
Auriculotemporal nerve
Maxillary nerve
Chorda Tympani