Subfascial and submuscular methods of temporal muscle dissection and their relationship to the frontalis branch of the facial nerve

TLDR

Microsurgical anatomy of the temporal and zygomatic facial nerve branches and adjacent superficial temporal artery vasculature is described as encountered during subfascial and submuscular temporal muscle dissection for anterolateral craniotomies. The study evaluates subfascial and submuscular temporal muscle dissections as alternatives to the interfascial technique in anterolateral craniotomies. Twenty sides from ten latex‑injected cadavers were dissected via pterional and orbitozygomatic approaches using subfascial or submuscular temporal muscle techniques to expose the facial nerve branches and STA. The temporal nerve rami lie within the galeal plane, the zygomatic branch courses deeper than the superficial musculoaponeurotic layer, and the frontal branch of the STA serves as a key landmark, so that meticulous use of these landmarks during subfascial or submuscular dissection provides a safe and expeditious alternative to the traditional interfascial technique.

Abstract

The microsurgical anatomy of the temporal and zygomatic branches of the facial nerve are presented along with related local vasculature (frontal and parietal branches of the superficial temporal artery [STA]) as encountered when using subfascial and submuscular temporal muscle dissection techniques for anterolateral craniotomies. Twenty sides were studied in 10 cadaveric specimens that had been previously injected with latex. The rami of the temporal and zygomatic branches of the facial nerve and branches of the STA were dissected out through pterional and orbitozygomatic approaches by using a submuscular or subfascial temporal muscle dissection technique. The three rami of the temporal branch of the facial nerve (the auricularis, frontalis, and orbicularis) were found to run within the galeal plane of the scalp. The zygomatic branch of the facial nerve was found to course deeper than the most caudal extension of the galea, known as the superficial musculoaponeurotic layer. The frontal branch of the STA served as an important landmark for the subfascial or submuscular dissections because excessive reflection of the scalp flap inferior to the level of this vessel would inadvertently injure the frontalis branch of the facial nerve. Subfascial and submuscular dissections of the temporal muscle offer an alternative to the interfascial technique during anterolateral craniotomies. Scalp and temporal dissection performed with careful attention to anatomical landmarks (frontal branch of the STA and the suprafascial fat pad) provides a safe and expeditious alternative to the traditional interfascial technique.