The facial nerve is the seventh (VII) of twelvepaired cranial nerves.It arises from the brainstem between the ponsand the medulla, and controls the muscles offacial expression.
Emerging from beneath the parotid gland upon the masseter muscle, it receives the ventral branch of the superficial temporal nerve, and divides into dorsal and ventral buccal branches.
The following collateral branches are given off, the first five being detached within the facial canal, and the others between the stylo-mastoid foramen and the border of the jaw. 1.The great superficial petrosal nerve (N. petrosus superficialis major) arises from the geniculate ganglion.
2. A delicate branch arises from the geniculate ganglion and unites with a filament issuing from the tympanic plexus to form the small superficial petrosal nerve. 3.The stapedial nerve (N. stapedius) which innervates the stapedius muscle.
4.The chorda tympani is a small nerve which arises a little below the previous and pursues a regular(persistent) course in a small canal in the mastoid part of the temporal bone (Canaliculus chordae tympani), to reach the tympanic cavity. 5. Anastomotic filaments unite with the auricular branch of the vagus near the stylomastoid foramen.
6. The posterior auricular nerve (N. auricularis aboralis) arises from the facial at its emergence from the facial canal.
7.The internal auricular nerve (N. auricularis internus) springs from the facial close to or in common with the posterior auricular nerve.
8. The digastric branch (R. digastricus) arises from the facial below the auricular nerves and descends under cover of the parotid gland. 9. The auriculo-palpebral nerve (N.auriculopalpebralis) arises from the upper edge of the facial near the posterior border of the ramus.
10. The cervical branch (R. colli) is small; it arises from the ventral border of the facial opposite to the preceding(previous) nerve.
The facial nerve usually terminates after a short course on the surface of the masseter by dividing into two buccal branches. The dorsal buccal nerve (N. buccalis dorsalis) Ventral buccal nerve (N. buccalis ventralis