Finally, to test the motor division of the mandibular branch, ... Kochhar A, Larian B, Azizzadeh B. Facial nerve and parotid gland anatomy. Otolaryngol Clin North Am 2016;49:273-284.

The mandibular nerve. This branch of the trigeminal nerve has both sensory and motor parts. It carries sensations from the lower part of your face, including the jaw, lower lip, and gums.