CNVII Facial Nerve

Authors

Affiliations

Nathaniel Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Somatic motor Pathway:

Motor: Pre-central gyrus -> Corticobulbar tract (1°) -> (Pontomedullary junction) Facial motor nucleus -> Facial nerve (2°) -> Muscles of facial expression

Parasympathetic Motor Pathway:

Lacrimal / nasal mucosa: Hypothalamus -> Dorsal longitudinal Fasciculus -> Superior Salivatory Nucleus (2° Synapse) -> Pterygopalatine ganglion (3° Synapse) -> Lacrimal gland + Nasal Mucosa Gland

Submandibular/Sublingual: Hypothalamus -> Dorsal Longitudinal Fasciculus -> Superior Salivatory nucleus (2° Synapse) -> Lingual Nerve -> Submandibular ganglion (3° Synapse) -> Submandibular / Sublingual gland

Special sense (2/3 Taste) Pathway:

Sensory cortex (Gustatory area) -> Ventral Posterior Medial Nucleus of Thalamus (VPM) (2° Synapse) -> Nucleus Solitarius (3° Synapse) -> Tractus solitarius -> -> Geniculate Ganglion -> Chorda Tympani -> RUN W/ Lingual nerve (V3) -> Taste Anterior 2/3 tongue

Dysfunction

• Hyperacusis (sensitivity to sound due to innervation of inner ear bones: stapedius)
• Decreased lacrimation
• Absence of taste on anterior 2/3 of tongue
• Facial muscle palsy
  • Bell’s palsy is an example of CN VII paralysis

DDX

Facial CN VII lesions vs UMN lesions:

• Facial = weakness on half of the face
• UMN: weakness on one half (but only the lower 2/3 = forehead not affected)