Affected Muscles:
- Depressor Labii Inferioris - Depresses lower lip.
- Mentalis - Elevates and protrudes lower lip and pulls skin of chin up.
- Risorius - Draws angle of mouth laterally.
- Orbicularis Oris - Closes and protrudes lips.
- Levator Labii Inferioris - Raises upper lip.
Mechanism of Muscle Weakness
This is because the facial nerve (VII) that is responsible for transmitting signals to the facial muscles gets inflamed and swollen, leading to weakness of the muscles. This inflammation leads to squeezing of the nerve as it courses through the facial canal, resulting in sudden objective weakness or paralysis of the facial muscles.
Other Symptoms:
- Dryness of the affected eye.
- Altered taste sensation.
- Sensitivity to light.
- Hyperacusis
- Drooling