NAMES OF THE MUSCLES, THEIR ORIGIN, INSERTION, AND ACTIONS
1. Platysma
- Origin: Fascia over deltoid and pectoralis major muscles
- Insertion: Mandible, blends with muscles around angle of mouth, and skin of lower face
- Action: It depresses mandible and draws outer part of lower lip inferiorly and posteriorly (pouting).
2. Mentalis
- Origin: Mandible
- Insertion: Skin of chin
- Actions: It raises and protrudes or stick out lower lip as it wrinkles on the chin (pouting).
3. Orbicularis oris
- Origin: Muscle fibers surrounding opening of the mouth
- Insertion: Skin at corner of mouth
- Actions: It closes and protrudes lips (kissing), compresses lips against teeth, and shapes lips during speech.
4. Corrugator supercilli
- Origin: Medial end of supercilliary arch of frontal bone
- Insertion: Skin of eyebrow
- Actions: Draws the eyebrow inferiorly and wrinkles skin of forehead vertically (frowning).
5. Orbicularis oculi:
- Origin: Medial wall of orbit
- Insertion: Circular path around orbit
- Actions: It blinks and closes eyes.
6. Occipitofrontalis (frontal belly*)
- Origin: Frontal belly - Epicranial aponeurosis
- Insertion: Skin superior to supraorbital margin
- Actions: It wrinkles skin of forehead, raises eyebrows and draws scalp anteriorly.
REFERENCES
- Tortora, G. J., & Derrickson, B. (2017). The Muscular System . In Principles of anatomy and physiology (15th ed., pp. 357–413). essay, Wiley Custom Learning Solutions.
- Marieb, E. N., & Keller, S. M. (2022). The Muscular System . In Essentials of human anatomy & physiology (13th ed.). essay, Pearson Education Limited.