The mandibular marginal branch of the nerve is an important branch of the facial nerve. The mandibular marginal branch of the facial nerve originates from the midpoint of the line between the angle of the mandible and the earlobe, most of it exits superficially from the lower edge of the parotid gland, and a few of it exits the parotid gland at the turning point of the anterior edge and the anterior-inferior edge, and then it is sent out with a slight arc, and then it goes from the posterior edge of the masticatory muscle at the point of attachment to the deep surface of the chin muscle, and then it travels along the lower edge of the lower body of the mandible. In its anterior course, the mandibular marginal branch continuously sends out secondary branches, and the upper branch anastomoses with the lower branch of the buccal branch to innervate the orbicularis oculi muscle of the upper lip, while the lower branch innervates the descending coracobrachialis muscle, descending inferior labialis muscle, chin muscle, and part of the orbicularis oculi muscle. The mandibular marginal branch of the facial nerve has a long travel distance and a small diameter, which is easy to be damaged and not easy to be compensated in plastic surgery, and the damage manifests itself in the form of crooked corners of the mouth, which seriously affects the aesthetics, so the preoperative preparation should be adequate. If you have symptoms of mandibular marginal branch nerve injury, you need to seek professional medical treatment in time to avoid delaying your condition.