Affected muscles:
- Frontalis - elevates the eyebrows and wrinkles the forehead.
- Orbicularis oculi - closes the eyelids, responsible for blinking and squinting.
- Platysma - pulling down the mandible, opens the mouth, and pulling the corners of the lips
- Orbicularis oris - loses and puckers the lips
- Buccinator - compresses the cheek
Mechanism of Muscle Weakness:
Bell’s palsy is a condition that causes sudden weakness of muscles one one side of the face (unilateral facial paralysis). It occurs when there is inflammation of the 7th cranial nerve, which usually triggered by viral infections such as HIV and Lyme disease. Inflammation leads to compression and temporary damage of the nerve as it passes through the narrow facial canal in the skull, disabling contraction of muscles that causes leading facial droop on the affected side.
Other symptoms:
- Decreased tearing
- Aching of the ear
- Drooling due to weakness of the muscles around the mouth
- Tingling or numbness of cheek or mouth
- Increased sensitivity to sound (hyperacusis)