CN VII: Facial Nerve Flashcards
From where does the CN VII emerge?
pontomedullary groove
Exits through which foramen?
internal acoustic meatus/internal auditory canal
After the internal acoustic meatus the facial nerve splits into 3 branches. What are these branches (and their foramen)?
- greater petrosal branch (petrous portion of temporal bone)
- chorda tympani branch (petrotympanic fissure)
- somatic branch (stylomastoid foramen)
What are the branches of the somatic branch?
- Temporal
- Zygomatic
- Buccal
- Mandibular
- Cervical
Before it branches, what does the somatic branch supply motor innervation to?
- muscles of facial expression (frontalis, orbicularis oris, etc.)
- stapedius muscle of ear (dampens vibrations)
What’s unique about the stapedius muscle of the ear?
Smallest muscle in the body
What do the branches of the somatic branch (SB) have in common?
They all pass through the parotid gland
What is the parasympathetic function of the chorda tympani (CTB) branch?
- submandibular salivary gland
- sublingual salivary gland
Does parasympathetic innervation cause salivary glands to secrete or dry up?
Secrete
What is the special sensory aspect of the chorda tympani (CTB) branch?
carries taste from anterior 2/3 of tongue
- joins up with lingual nerve
What is the parasympathetic function of the greater petrosal (GPB) branch?
- lacrimal gland
- mucus secreting glands of nasal cavity
(“the break-up nerve”)
What is the sensory function of the greater petrosal (GPB) branch?
General sensory info for small portion behind ear
Pathology/disorders?
- drying of eye (GPB)
- drying of mouth (CTB)
- loss of taste (CTB)
- hyperacusis (over sensitivity with hearing; SB)
- paralysis of facial expression (SB)
- Bell’s palsy
CN VII is one of four cranial nerves with parasympathetic functions. What are the other three?
- occulomotor (CN III)
- glossopharyngeal (CN IX)
- vagus (CN X)
