Case examples 
Marginal mandibular nerve palsy
Marginal mandibular nerve palsy, dependent on injury level, will result in both inferior lip depression and lip eversion weakness. Inability to lower the lateral lip downwards and laterally (figure 3a) and eversion of the vermillion border (figure 3b) results in elevation of the ipsilateral side with apparent dropping of the contralateral9.
Pseudo palsy of the Marginal Mandibular Nerve
Transection of the platysma or cervical nerve causing ‘pseudo-marginal mandibular nerve palsy’ will result weakness of depression, palpable and visible lack of platysmal function below the level of transection (figure 4a). However, pouting will remain intact through mentalis function (figure 4b). Such patients may refrain from a “full-denture type’ smile to disguise their palsy.