ANATOMY OF THE FRONTOTEMPORAL BRANCH OF THE FACIAL-NERVE AND INDICATIONS FOR INTERFASCIAL DISSECTION

INTRODUCTION: Many studies have been conducted of the surgical anatomy of the frontotemporal branch of the facial nerve (FTBFN). However, ve ry few have addressed the indications for interfascial dissection. Whe n the zygomatic arch needs to be exposed, the interfascial approach is recommended to protect the FTBFN. With the transbasal or subfrontal a pproaches, however, when a bicoronal skin incision is used, the need f or the interfascial approach is not clear. METHODS: We studied 10 temp oral regions (5 cadaveric heads). We dissected the recognized fascial layers of the temporal region and the FTBFN. We performed a histologic al study in a sixth specimen. RESULTS: We observed the following. 1) T he galea and the superficial layer of the deep temporal fascia become fused in a curved line from the lateral orbital border 2.8 cm above th e zygomatic arch to a point 3 cm posterior to the inferolateral angle of the orbit. 2) After this transitional area of adherence, the subgal eal loose cellular layer is lost and is replaced by a fibrofatty tissu e. 3) The FTBFN in its course above the zygomatic arch runs in this ti ssue layer without being protected by the galea. 4) Over the superolat eral angle of the orbital rim, the galea protects FTBFN, and there are no subgaleal adhesions in that area. CONCLUSION: Above the zygomatic arch, the FTBFN is not protected by the galea. During bicoronal approa ches, if only the superolateral angle of the orbital rim needs to be e xposed and not the zygomatic arch, there is no need to protect the FTB FN using an interfascial approach.