Figure 3. Asymmetrical smile in a patient following left parotid to my and MRND with sacrifice of the marginal mandibular nerve (true palsy). 3a. Paralysis of the lip depressor with apparent drooping of the contralateral side. 3b. Asymmetrical pouting caused by inability to evert the left side of the lower lip
Figure 4. Asymmetrical smile of a patient following a right MRND with preservation of the marginal mandibular nerve (i.e. pseudo-palsy). 4a. Note weakness of the lip depressors on the right side. 4b. The function of the marginal mandibular nerve allows bilateral eversion of the lower lip when pouting. (i.e. pseudo-palsy)