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.