ObjectiveIn head and neck ablative surgery, traditional teaching is that the key facial nerve branch to preserve along the plane of the lower border of the mandible is the marginal mandibular branch (MMb), which is considered to control all lower lip musculature. The depressor labii inferioris (DLI) is the muscle responsible for pleasing lower lip displacement and lower dental display during natural emotive smiling.Study DesignTo understand the structure/function relationships of the distal lower facial nerve branches and lower lip musculature.SettingIn vivo extensive facial nerve dissections under general anesthesia.MethodsIntraoperative mapping was performed in 60 cases, using branch stimulation and simultaneous movement videography.ResultsIn nearly all cases, the MMb innervated the depressor anguli oris, lower orbicularis oris, and mentalis muscles. The nerve branches controlling DLI function were identified 2 ± 0.5 cm below the angle of the mandible, originating from a cervical branch, separately and inferior to MMb. In half of the cases, we identified at least 2 independent branches activating the DLI, both within the cervical region.ConclusionAn appreciation of this anatomical finding may help prevent lower lip weakness following neck surgery. Avoiding the functional and cosmetic consequences that accompany loss of DLI function would have a significant impact on the burden of potentially preventable sequelae that the head and neck surgical patient frequently carries.
Management of facial palsy is targeted toward correction of individual patient concerns. Both esthetic perioral changes to the face and functional perioral deficits are commonly concerning to patients with facial paly. Herein, we review perioral impairments resulting from both flaccid and postparalytic facial palsy. Additionally, we discuss targeted therapy and a multitude of technical interventions aimed at restoring perioral functionality to optimize oral competence, speech articulation, and quality of life for facial palsy patients.
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