The Facial Nerve: The Path of Its Branches to the Muscles of the Infraorbital Region that Lift the Upper Lip in Relation to the Deep Fascia of the Midface

The mimetic muscles are innervated by the facial nerve. The function of these muscles is very important because they partecipate to the eye protection, the speach and the nutrition. Furthermore from an evolutionary point of view the facial expressions are a major way of communication between human beings. Classic anatomy describes the path of the branches of the facial nerve in the midface, anterior to the parotid fascia, as running in the subcutaneous tissue, a recent study related to the fascial layers of this region has shown that a deep fascia exists in the infraorbital region, it continues from the temporal area and it covers the mimetic muscles that lift the upper lip. The aim of this study is to describe the path of the branches of the facial nerve in this facial area in relation to the deep fascia recently described. Materials and Methods 24 hemifaces have been dissected at the Laboratoire d'Anatomie de Paris Descartes to study the relationship between the branches of the facial nerve and the deep fascia of the infraorbital region. Results This study demonstrates that the branches of the facial nerve that go to the muscles of the infraorbital region are always covered and protected by the deep fascia of this region. Some branches run deep to the muscles, on the contrary some run superficial to the zygomaticus major, minor, levaetor labii superioris etc and anastomize with other branches to reach the glabellar region, all these branches run deep to the deep fascia. Conclusions The existance of a deep fascia in the infraorbital region has been shown. This fascia covers and protects the branches of the facial nerve that run to the muscles that lift the upper lip, this finding changes the classic anatomical concept of the facial nerve running without protection in the subcutaneous tissue of the midface and it has important implications in both descriptive and applied anatomy.