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The facial muscles are a group of striated skeletal muscles supplied by the facial nerve (cranial nerve VII) that, among other things, control facial expression. These muscles are also called mimetic muscles. They are only found in mammals, although they derive from neural crest cells found in all vertebrates.
The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue.
Branches of the facial nerve leaving the facial motor nucleus (FMN) for the muscles do so via both left and right posterior (dorsal) and anterior (ventral) routes. In other words, this means lower motor neurons of the facial nerve can leave either from the left anterior, left posterior, right anterior or right posterior facial motor nucleus.
The facial nerve (VII) and vestibulocochlear nerve (VIII) both enter the internal auditory canal in the temporal bone. The facial nerve then reaches the side of the face by using the stylomastoid foramen, also in the temporal bone. Its fibers then spread out to reach and control all of the muscles of facial expression.
The mandibular nerve (V 3) carries sensory information from the lower lip, the lower teeth and gums, the chin and jaw (except the angle of the jaw, which is supplied by C2-C3), parts of the external ear and parts of the meninges. The mandibular nerve carries touch-position and pain-temperature sensations from the mouth.
The zygomatic branches of the facial nerve (malar branches) are nerves of the face.They run across the zygomatic bone to the lateral angle of the orbit.Here, they supply the orbicularis oculi muscle, and join with filaments from the lacrimal nerve and the zygomaticofacial branch of the maxillary nerve (CN V 2).
Muscle Action Risorius: Smirk Buccinator: Aids chewing by holding cheeks flat Levator labii superioris: Elevates upper lip Levator labii superioris alaeque nasi muscle: Snarl Levator anguli oris: Soft smile Nasalis: Flare nostrils Orbicularis oris muscle: Purse Lips Depressor septi nasi: Depresses nasal septum Procerus: Moves skin of forehead
Many voluntary movements rely on spinal lower motor neurons, which innervate skeletal muscle fibers and act as a link between upper motor neurons and muscles. [2] [3] Cranial nerve lower motor neurons also control some voluntary movements of the eyes, face and tongue, and contribute to chewing, swallowing and vocalization. [4]