Muscles affected by Bell’s Palsy
- corrugator supercilii - Draws eyebrow inferiorly and wrinkles skin of forehead vertically as in frowning.
- occipitofrontalis (frontal belly) - Draws scalp anteriorly, raises eyebrows, and wrinkles skin of forehead horizontally as in look of surprise.
- orbicularis oculi - Closes eye
- orbicularis oris - Closes and protrudes lips, as in kissing; compresses lips against teeth; and shapes lips during speech.
- 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).
Mechanisms of muscle weakness
- The muscle weakness experienced in Bell’s Palsy is due to the damage or inflammation of the facial (VII) nerve, the nerve which controls the muscles in the face. This causes a paralysis in one side of the face and weakens the affected muscles. Its cause may sometimes be associated with diabetes, high blood pressure, lyme disease, among others.
Other symptoms
- dry eyes due to the inability to close eye on affected side of the face
- disordered movement of the muscles that control facial expressions
- loss of feeling or sensation in the face
SOURCES:
Bell’s Palsy. (2023, March 8). Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/conditions-and-diseases/bells-palsy
Tortora, G. J., & Derrickson, B. (2017). Principles of Anatomy & Physiology. http://ndl.ethernet.edu.et/bitstream/123456789/1717/1/36%2c2012.pdf.pdf