In general terms, the muscles involved in producing different facial expressions are all ultimately supplied by the seventh cranial nerve (=facial nerve). This nerve springs from the brainstem at the level of the pontomedullary junction, inferolateral to the origin of the sixth cranial nerve and superomedial to the origin of the eighth cranial nerve. There are three principal origins in the head and neck region providing the nervous supply to the superficial structures of the face and scalp: The facial nerve consists of three types of fibres, motor, sensory and autonomic (secretomotor, i.e. parasympathetic), which supply numerous structures of the head and neck. The facial sensory nerve supply is provided by the fifth cranial nerve. This is the sole cranial nerve to have a direct origin from the pons. The nerve forms three divisions, namely, the ophthalmic (V1), maxillary (V2) and mandibular (V3), each of which innervates a particular facial territory. The muscles of the face involved in chewing, i.e. the medial pterygoid, lateral pterygoid, temporalis and masseter, are also innervated by the fifth cranial nerve.