Affected Muscles:
- Occipitofrontalis: Raises the eyebrows and wrinkles the forehead
- Orbicularis oculi: Closes the eyelids
- Buccinator: Compresses the cheeks against the teeth
- Levator labii superioris: Elevates the upper lip
- Orbicularis oris: Closes and puckers the lips
Mechanism of Muscle Weakness:
Caused by inflammation, compression, or damaging of the facial nerve (Cranial Nerve VII), which controls the muscles of facial expression, which causes the nerves to be unable to transmit signals to the muscles resulting to muscle paralysis or weakness.
Other Symptoms:
- Increased drooling due to weakness of muscles around the lips
- Dry eyes due to inability to close eyes
- Loss of taste
- Difficulty speaking and forming certain sounds