Why Does My Lower Lip Tremble When I Try to Smile?
1. Introduction A trembling lower lip when trying to smile is fundamentally a manifestation of localized muscle fatigue, heightened autonomic arousal, or an essential tremor affecting the delicate facial musculature. When the intricate muscles that control the lips are engaged, an underlying hyper-excitability of the facial nerve can cause the motor units to fire asynchronously, … Read more