Examine the buccinator muscle and the associated nerves. Identify the buccal branch of the mandibular nerve which provides cutaneous sensation to the zygomatic region and sensory innervation to the vestibule of the oral cavity, it does not innervate the buccinator muscle. The buccal branch of the facial nerve runs laterally over the masseter muscle and onto the buccinator muscle to provide it with motor innervation.
Remember that all muscles of facial expression are innervated by CN VII and all muscles of mastication are supplied by the motor division of the mandibular nerve (V3).
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