Review of Facial Nerve

A Review of Facial Nerve Anatomy
Terence M. Myckatyn, M.D.1 and Susan E. Mackinnon, M.D.1

ABSTRACT

An intimate knowledge of facial nerve anatomy is critical to avoid its inadvertent injury during rhytidectomy, parotidectomy, maxillofacial fracture reduction, and almost any surgery of the head and neck. Injury to the frontal and marginal mandibular branches of the facial nerve in particular can lead to obvious clinical deficits, and areas where these nerves are particularly susceptible to injury have been designated danger zones by previous authors. Assessment of facial nerve function is not limited to its extratemporal anatomy, however, as many clinical deficits originate within its intratemporal and intracranial components. Similarly, the facial nerve cannot be considered an exclusively motor nerve given its contributions to taste, auricular sensation, sympathetic input to the middle meningeal artery, and parasympathetic innervation to the lacrimal, submandibular, and sublingual glands. The constellation of deficits resulting from facial nerve injury is correlated with its complex anatomy to help establish the level of injury, predict recovery, and guide surgical management.
KEYWORDS: Extratemporal, intratemporal, facial nerve, frontal nerve, marginal mandibular nerve

he anatomy of the facial nerve is among the most complex of the cranial nerves. In his initial description of the cranial nerves, Galen described the facial nerve as part of a distinct facial-vestibulocochlear nerve complex.1,2 Although the anatomy of the other cranial nerves was accurately described shortly after Galen’s initial descriptions, it was not until the early 1800s that Charles Bell distinguished the motor and sensory components of the facial nerve.3,4 Facial nerve anatomy is categorized in terms of its relationship to the cranium or temporal bone (intracranial, intratemporal, and extratemporal) or its four distinct components (branchial motor, visceral motor, general sensory, and

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