CNVII Facial Nerve

Authors
Affiliations

Nate 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

Path of the facial and intermediate nerves1

Path of the facial and intermediate nerves

The path and connections of CN VII Facial nerve in the temporal bone1

The path and connections of CN VII Facial nerve in the temporal bone

Path of the upper portions of the CN IX Glossopharyngeal, CN X Vagus, and CN XI Accessory1

Path of the upper portions of the CN IX Glossopharyngeal, CN X Vagus, and CN XI Accessory

Upper part of medulla spinalis, hindbrain, and midbrain (posterior view)1

Upper part of medulla spinalis, hindbrain, and midbrain (posterior view)

Somatic motor Pathway:

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

Figure 1: 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)

Palsy

Causes

Lyme disease

References

1.
Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/
2.
Betts JG, Blaker W. Anatomy and Physiology. 2nd ed. OpenStax; 2022. https://openstax.org/details/books/anatomy-and-physiology-2e/?Book%20details
3.
Roos KL. Neurologic Complications of Lyme Disease. CONTINUUM: Lifelong Learning in Neurology. 2021;27(4):1040-1050. doi:10.1212/CON.0000000000001015

Citation

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