N3 Anatomy and Physiology (1st Sem AY 2022-2023)

Five muscles that are affected by Bell’s Palsy

1. Orbicularis oculi
   Action: closes the eyes

2. Corrugator supercilii
   Action: draws the eyebrow inferiorly and creates vertical wrinkles on the skin of forehead

3. Zygomaticus major
   Action: raises upper lip which exposes maxillary teeth

4. Buccinator
   Action: presses cheeks against teeth and lips; draws corner of mouth laterally; and assists in chewing

5. Occipitofrontalis (Frontal Belly)
   Action: draw the scalp anteriorly raises the eyebrows, and wrinkles the skin of the forehead horizontally

          Bell’s palsy is a condition in which the muscles of facial expression are unilaterally paralyzed, which is caused by the damage of the disease of the facial (VII) nerve. Some causes include herpes simplex virus infection, facial nerve injury during ear surgery, or inflammation of the facial nerves as a result of an ear infection. Since one side of the face is paralyzed, a person with Bell’s palsy could have difficulty or may not be able to wrinkle their forehead, close their eye, or pucker lips on the affected side. They may also experience drooling and swallowing difficulties. The symptoms of Bell’s palsy are quite similar to those of a stroke. Other symptoms of Bell’s palsy as a result of muscle weakness are loss of sense of taste, changes in the number of tears, and headache. 

Reference: 

Tortora, & Derrickson. (2012). Chapter 11: The Muscular System. In Principles of anatomy and physiology (13th ed.)