Facial nerve anatomy in eyelids and periorbit.

PURPOSE To clarify anatomically the facial nerve branches in the eyelids and periorbit. METHODS The facial nerve branches of the left periorbits from 31 Japanese cadavers were dissected under a surgical microscope. RESULTS The temporal, zygomatic, and deep buccal branches assembled posterior to the orbicularis oculi from its temporal or inferior side, and formed a dense plexus. The superficial buccal branches coursed, unlike the others, around the inferior nasal margin of the orbicularis oculi with some variations. The branches always passed across the "triangular window" that was outlined by the orbicularis oculi, the zygomaticus minor, and the levator labii superioris alaeque nasi. Then the branches crossed over the medial palpebral ligament, reaching both the procerus and corrugator supercilii in 94% of the specimens. The branches ramified the lower part of the orbicularis oculi in 65% and the upper part in 42% of the specimens. CONCLUSIONS The superficial buccal branches are the main supplier to the muscles in the nasal periorbit. This anatomical finding may be important information for accurate procedures in facial nerve surgery.