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Lagophthalmos

Anatomy & Function of {the} Facial Nerve

  • The facial nerve (CNVII) has two major divisions and controls {the} muscles of facial expression, including {the} frontalis muscle (raises {the} eyebrows), {the} orbicularis oculi muscle (closes {the} eyes), {the} zygomaticus muscles (raises {the} angle of {the} mouth)

Branches

  • Greater petrosal nerve - provides parasympathetic innervation to lacrimal gland, sphenoid sinus, frontal sinus, maxillary sinus, ethmoid sinus, nasal cavity, as well as special sensory taste fibers to {the} palate via {the} Vidian nerve.
  • Nerve to stapedius - provides motor innervation for stapedius muscle in middle ear
  • Chorda tympani - provides parasympathetic innervation to submandibular gland and sublingual gland and special sensory taste fibers for {the} anterior 2/3 of {the} tongue.

Etiologies

  • Paresis of {the} orbicularis oculi muscle leads to a diminished blink, incomplete eyelid closure (Lagophthalmos), impairment of {the} nasolacrimal pumping system
    • The blink reflex and lid position are critical to maintain {the} ocular surface
    • Each blink spreads {the} tear film over {the} ocular surface and allows for a continuous layer of moisture.
  • Congenital
    • Moebius' Syndrome
  • Acquired
    • Bell's Palsy
    • vascular lesions
  • Tumors Trauma
    • Acoustic Neuroma
    • Parotid gland
    • temporal bone tumor

Symptoms

  • Tearing, atonic eyelid

Terms

Lagophthalmos: Patients with lagophthalmos have an inability to close eyelids. This might possibly occur, for instance, in patients with Thyroid eye disease. Visit {the} lagophthalmos page for more details.

Anatomy  & Function of the Facial Nerve