The aim of this review was to familiarize the reader with critical facial nerve anatomy relating to facial rejuvenation surgeries.
The temporal branch to the upper orbicularis oculi muscle (OOM): The temporal branch was under the temporoparietal fascia above the zygomatic arch and divided into 2 to 4 branches. The highest level of the twigs that entered the OOM on the x axis and the y axis with the origin of the lateral canthus is +2.51 ± 0.23 cm and +2.70 ± 0.35 cm; and the lowest, 0 cm and +2.68 ± 0.32 cm, respectively. The zygomatic and the buccal branch to the lower OOM: All pretarsal and preseptal OOMs were innervated by 5 to 7 terminal twigs of the zygomatic branches of the facial nerve that approached the muscle at a right angle. The medial portion of the lower OOM was innervated by 1 to 2 terminal twigs of the buccal branch, and the middle portion was innervated with 2 to 3 twigs of the zygomatic branch. The lateral portion was supplied by the uppermost zygomatic branch, which split into 2 to 4 twigs. The temporal branch to the corrugator supercilii muscle: A plexus mainly from the inferior ramus partly from the middle ramus of the temporal branch of the facial nerve enters the corrugator supercilii muscle in the supraorbital area. The temporal branch has as many as 4 to 7 rami, with interconnection among them. The buccal branch to the procerus muscle: The buccal branch crosses the intercanthal line (the nasion to the medial canthus) at approximately one third laterally. The nerve entrance was within a circle with a diameter of 5 mm, and its center was located 9 mm lateral and 10 mm superior from the nasion. It was approximately at the midpoint of the lateral half of the intercanthal line and the lower one third between the intercanthal line and the tangential line of the supraorbital rim. The buccal branch, the buccal fat pad, and the parotid duct: The buccal branches and the parotid duct crossed each other within a semicircle with a 30-mm radius. The base (diameter) was parallel to a horizontal line passing the corner of the mouth and 12 mm above. Its center was located 53 mm lateral to it. The buccal branches of the facial nerve have 2 locations at the buccal fat pad: type I, branches crossing superficial to the buccal fat pad in 14 (73.7%) of 19 specimens, and type II, 2 twigs passing through the buccal extension of the buccal fat pad in 5 (26.3%) of 19 specimens. The buccal branch to the upper orbicularis oris muscle: Approximately 4 branches (4.06 ± 0.83) entering the pars marginalis were found. Most ramifying points (14/17, 82%) were located within a circle with a 5-mm radius, and the center was 12 mm lateral and 26 mm superior to the mouth corner. The mandibular branch according to the neck position: At the one-fourth point, the border-nerve distance decreased (4.32 ± 2.60 mm) with the neck in ipsilateral rotation and the border-nerve distance increased (5.97 ± 2.62 mm) with the neck in contralateral rotation.
We hope that this knowledge will aid surgeons in achieving successful outcomes.