1. Muscles & Actions
a) Frontal belly: Draws scalp anteriorly, raises eyebrows, and wrinkles skin of forehead horizontally as in look of surprise
b) Buccinator: Presses cheeks against teeth and lips, as in whistling, blowing, and sucking; draws corner of mouth laterally; and assists in mastication (chewing) by keeping food between the teeth (and not between teeth and cheeks
c) Orbicularis oris: Closes and protrudes lips, as in kissing; compresses lips against teeth; and shapes lips during speech
d) Zygomaticus major: Draws angle of mouth superiorly and laterally, as in smiling
e) Levator labii superioris: Raises upper lip
2. Mechanism of muscle weakness: Bell's palsy could be a result of swelling, irritation, infection, or damage of the facial nerve due to an ear infection, ear surgery, or herpes simplex virus. When the facial nerve is compromised, the affected muscles cannot receive proper signals from the brain, leading to muscle weakness or paralysis on one side of the face.
3. Other symptoms: Drooling and difficulty in swallowing, cannot wrinkle the forehead, close the eye, or pucker the lips