Muscles Affected by Bell's Palsy
frontalis- draws the scalp anteriorly and posteriorly, raises the eyebrows, and wrinkles the skin of the forehead horizontally
orbicularis oculi- closes eye
orbicularis oris- closes, protrudes, and compresses lips; shapes lips during speech
buccinator- presses cheeks against the teeth; draws corner of mouth laterally; assists in mastication
platysma- draws outer part of lower lip inferiorly and posteriorly; depresses mandible
Mechanism of Muscle Weakness
Bell’s palsy, also known as facial paralysis, is a unilateral paralysis of the muscles of facial expression. It is due to damage or disease of the facial (VII) nerve. Possible causes include inflammation of the facial nerve due to an ear infection, ear surgery that damages the facial nerve, or infection by the herpes simplex virus. The paralysis causes the entire side of the face to droop in severe cases. The person cannot wrinkle the forehead, close the eye, or pucker the lips on the affected side.
Other Symptoms
Drooling
difficulty in swallowing and chewing
pain or numbness behind the ears
headaches
decrease in ability to taste