A 43-year-old teacher underwent left parotidectomy. Upon awakening from surgery, paralysis of the left lower lip was observed. This complication was most likely due to injury to which of the following:
The cervical branch of the facial nerve innervates the lower lip through the marginal mandibular branch of the nerve . As no cross innervation exits to other branches of the facial nerve, marginal mandibular branch injuries always yield paralysis of the same side of the lower lip. Injuries of the main trunk of the facial nerve or its temporal branch would usually produce upper facial paralysis as well.
Parotid duct
Facial nerve temporal branch
Facial nerve cervical branch
Facial nerve main trunk
Salivary Glands