Muscles that are affected by Bell's Palsy
orbicularis oculi — action: closes eye
zygomaticus major — action: draws angle of mouth superiorly and laterally, as in smiling
zygomticus minor — action: raises (elevates) upper lip, exposing maxillary (upper) teeth
buccinator — action: presses cheeks against teeth and lips, as in whistling, blowing, and sucking; draws corner of mouth laterally; and assists in mastication by keeping foos between the teeth (and not between teeth and cheeks)
corrugator supercilii — action: draws eyebrow inferiorly and wrinkles skin of forehead vertically as in frowning
Tortora, G. J., & Derrickson, B. (2017). Tortora’s Principles of Anatomy and Physiology. In John Wiley & Sons, Inc. eBooks. https://ci.nii.ac.jp/ncid/BB23861293