Nerve
Facial nerve (CN VII)
One nerve serving expression, taste and secretion
High-yield
The greater petrosal pathway supports tearing and mucous secretion; chorda tympani carries anterior-tongue taste and secretomotor fibers for the submandibular and sublingual glands. CN VII passes through the parotid but does not provide its parasympathetic secretomotor supply.
Overview
CN VII combines a large motor root with the nervus intermedius, which carries sensory and parasympathetic fibers. Both emerge near the pontomedullary junction and travel with CN VIII toward the internal acoustic meatus. Within the temporal bone, branches separate for gland secretion, taste and stapedius. The main motor trunk exits through the stylomastoid foramen and branches across the face after passing through the parotid gland.
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Reference facts
- Origin
- Motor output arises from the facial motor nucleus; parasympathetic output from the superior salivatory/lacrimal region. Taste afferents relay in the rostral solitary nucleus and general sensory afferents in the spinal trigeminal nucleus; their cell bodies are in the geniculate ganglion
- Skull exit
- Main trunk: stylomastoid foramen. Greater petrosal fibers leave through their hiatus and cross the foramen-lacerum region toward the pterygoid canal; chorda tympani leaves the middle ear through the petrotympanic fissure
- Course
- Pontomedullary junction → internal acoustic meatus → labyrinthine, tympanic and mastoid facial-canal segments → stylomastoid foramen. Greater petrosal, stapedius and chorda tympani branches arise within the temporal bone. Posterior auricular and digastric/stylohyoid branches precede the terminal facial divisions in the parotid
- Motor
- Facial-expression muscles, stapedius, stylohyoid and posterior digastric. Parasympathetic fibers relay in the pterygopalatine ganglion for lacrimal and mucous glands, and in the submandibular ganglion for submandibular and sublingual secretion
- Sensory
- Taste from most of the anterior two-thirds of the tongue through chorda tympani and from the palate through the greater petrosal pathway; limited general sensation from the external-ear region, with overlapping neighboring nerve territories
Mnemonic
Trace the five terminal groups from superior to inferior: Temporal, Zygomatic, Buccal, Marginal mandibular, Cervical - T, Z, B, M, C.
Clinical correlation
Bell palsy is an acute peripheral facial palsy without an identified alternative cause. Poor eyelid closure can endanger the cornea. Ear pain and vesicles with facial palsy suggest Ramsay Hunt syndrome, although the rash may be delayed or absent. Injury beyond the stylomastoid foramen mainly affects facial movement while sparing the earlier taste, tearing and stapedius branches.
Frequently asked questions
Where does the facial nerve (CN VII) arise?
Motor output arises from the facial motor nucleus; parasympathetic output from the superior salivatory/lacrimal region. Taste afferents relay in the rostral solitary nucleus and general sensory afferents in the spinal trigeminal nucleus; their cell bodies are in the geniculate ganglion.
What muscles does the facial nerve (CN VII) supply?
Facial-expression muscles, stapedius, stylohyoid and posterior digastric. Parasympathetic fibers relay in the pterygopalatine ganglion for lacrimal and mucous glands, and in the submandibular ganglion for submandibular and sublingual secretion.
What is the sensory distribution of the facial nerve (CN VII)?
Taste from most of the anterior two-thirds of the tongue through chorda tympani and from the palate through the greater petrosal pathway; limited general sensation from the external-ear region, with overlapping neighboring nerve territories.
Where does the facial nerve (CN VII) leave the skull?
Main trunk: stylomastoid foramen. Greater petrosal fibers leave through their hiatus and cross the foramen-lacerum region toward the pterygoid canal; chorda tympani leaves the middle ear through the petrotympanic fissure.