Anatomical Considerations to Prevent Facial Nerve Injury

Abstract

Injury to the facial nerve during a face lift is a relatively rare but serious complication. A large body of literature has been dedicated toward bettering the understanding of the anatomical course of the facial nerve and the relative danger zones. Most of these prior reports, however, have focused on identifying the location of facial nerve branches based on their trajectory mostly in two dimensions and rarely in three dimensions. Unfortunately, the exact location of the facial nerve relative to palpable or visible facial landmarks is quite variable. Although the precise location of facial nerve branches is variable, its relationship to soft-tissue planes is relatively constant. The focus of this report is to improve understanding of facial soft-tissue anatomy so that safe planes of dissection during surgical undermining may be identified for each branch of the facial nerve. Certain anatomical locations more prone to injury and high-risk patient parameters are further emphasized to help minimize the risk of facial nerve injury during rhytidectomy.

Platysma‐sparing vascularized submental lymph node flap transfer for extremity lymphedema

“…The depressor anguli oris draws the lip downward and laterally, the depressor labii inferioris everts the vermilion border, and the mentalis acts to protrude the lower lip and wrinkles the skin of the chin. In patients with a full‐denture smile, the platysma co‐functions with the depressors to contribute significantly as a lip depressor . Ellenbogen was the first author to introduce the “marginal mandibular nerve pseudo‐paralysis” .…”

A conceptual framework for navigating the superficial territories of the face: Relevant anatomic points for the dermatologic surgeon

“…9. The facial nerve branches divide into a variable number of rami and in the mid lateral face form a plexus of interconnected communications (Zani et al, 2003;Roostaeian et al, 2015). 10.…”

“…As the Facial Nerve Branches Are Generally Protected by the SMAS, They Are Surgically Vulnerable at Points of Transition toward Their Destinations Vulnerability of the facial nerve and its branches during surgical exposure has made description of its course and distribution one of the most frequently visited topics (Liebman et al, 1982;Gosain, 1995;Larrabee and Henderson, 2000;Zani et al, 2003;Kwak et al, 2004;Odobescu et al, 2012;Mendelson and Wong, 2013;Brown et al, 2014;Roostaeian et al, 2015). Simply described, the facial nerve exits its intracranial course through the stylomastoid foramen and immediately gives off the posterior auricular nerve which passes behind the ear toward auricularis posterior and the occipital belly of occipitofrontalis muscles.…”

“…In this region, the branches lie deep to the SMAS and for procedures that are performed no deeper than the skin the facial nerve branches are less likely to be injured. Fortunately, these transition points are somewhat predictable and there is a growing bank of literature that provides detailed morphometric data to determine location and safe zones for minimizing risk for injury (Liebman et al, 1982;Ishikawa, 1990;Pogrel et al, 1996;Larrabee and Henderson, 2000;Zani et al, 2003;Kwak et al, 2004;Standring, 2008;Odobescu et al, 2012;Mendelson and Wong, 2013;Brown et al, 2014;Marur et al, 2014;Roostaeian et al, 2015). A brief account of these branches is presented below and more detailed description of their course is described in the relevant sections of the anatomic zones, (Fig.…”

“…There are a few basic concepts that remain crucial to understanding and predicting the challenges that accompany surgical manipulation of the superficial face: The face can be dissected through principle fascial planes: skin, subcutaneous fibroadipose layer, superficial musculoaponeurotic system (SMAS) plane, and deep fascial plane (Delmar, ; Mendelson and Wong, ). Muscles of facial expression attach to the dermis of the skin, are reinforced by retaining ligaments and arranged within a stepped configuration (Mendelson and Wong, ). The facial nerve is the principal motor supplier of the muscles of facial expression (mimetic muscles), primarily innervating them through their deep surfaces (Standring, ; Marur et al, ). The motor branches of the facial nerve exit the parotid fascia along its anterior margin, travel from a deep to superficial plane and lie deep to the SMAS plane (Zani et al, ). The SMAS splits to enclose the muscles of facial expression and is continuous with platysma, superficial parotid fascia, galea aponeurotica and superficial temporal fascia (temporoparietal fascia) (Ghassemi et al, ). The sub‐SMAS plane is a relatively avascular plane (Ghassemi et al, ). The trigeminal nerve branches exit the supraorbital, infraorbital and mental foramina and travel from deep to superficial direction toward the skin where they lie within the sub‐cutaneous fibroadipose layer (Randle et al, ; Standring, ; Sinnatamby, ; Yang et al, ). The facial artery and its branches travel deep to the SMAS and run along a superficial course to cross palpable bony boundaries or perforate the SMAS(Ishikawa, ; Coscarella et al, ). The facial nerve branches divide into a variable number of rami and in the mid lateral face form a plexus of interconnected communications (Zani et al, ; Roostaeian et al, ). Thickness of the subcutaneous layer varies significantly and form cosmetic units based on the distribution of fat compartments (more uniform in thickness over the scalp yet compaction of the subcutaneous tissue around the eyelids and lips appear to make this layer almost non‐existent) (Delmar, ; Erdogmus and Govsa, ; Turvey and Golden, ; Mendelson and Wong, ). …”