Answer:
The facial nerve is a mixed nerve containing motor, sensory and parasympathetic fibers. The nerve exits the skull at the stylomastoid foramen, runs anterolaterally between the bony styloid process and the stylohyoid muscle and posterior belly of the digastric muscle, and gives off the posterior auricular nerve which splits into a smaller auricular branch and a larger occipital branch. Within 1.5 cm of the stylomastoid foramen, the nerve enters the posteromedial border of the parotid gland. Here, the nerve almost immediately divides into temporofacial and cervicofacial divisions and then into temporal, zygomatic, buccal, marginal mandibular and cervical branches to innervate the facial muscle on their deep surface (with the exception of buccinator, mentalis, and the levator anguli oris which are innervated on their superficial surface).
Communication between the branches in the cheek (buccal and zygomatic) occurs in roughly 70%, whereas the frontal branches and the marginal mandibular branches had crossover in only 15%. The frontal (temporal) nerve emerges from beneath the parotid gland on a line extending from a point 0.5 cm below the tragus to a point 1.5 cm superior to the lateral aspect of the eyebrow. It enters the frontalis muscle on its deep surface at a point where the orbicularis oculi intersects the lateral aspect of the frontalis muscle (1.5 cm above the lateral aspect of the eyebrow). The mandibular branch is located about 1.0cm inferior to the mandibular margin, deep to the cervical fascia and 4.0 to 4.5 cm from the earlobe sulcus.
In the neck, the facial nerve innervates the platysma, the posterior belly of the digastric, and the stylohyoid muscle. Its sensory input is taste from the oral part of the tongue and palate, general sensations from the external acoustic meatus and concha, and proprioceptive afferents from the facial muscles.