Activity 1 - Name the muscle that may cause the following facial expression and write down its origin, insertion, and action.
1. Platysma
- Origin: (1) fascia over deltoid (2) pectoralis major muscles
- Insertion: mandible, blends with muscles around the angle of mouth and skin of lower face
- Action: Draws outer part of lower lip inferiorly (away from the head) and posteriorly (towards the head) as in pouting; depresses mandible
2. Mentalis
- Origin: mandible
- Insertion: skin of chin
- Action: elevates and protrudes lower lip; pulls the skin of the chin up, as in pouting
3. Orbicular Oris
- Origin: muscle fibers surrounding opening of mouth (modiolus)
- Insertion: skin at corner of mouth
- Action: closes and protrudes lips, as in kissing; compresses lips against teeth; shapes lips during speech
4. Corrugator supercilii
- Origin: medial end of superciliary arch of frontal bone
- Insertion: skin of eyebrow
- Action: draws eyebrow inferiorly (away from the head) and wrinkles skin of the forehead vertically, as in frowning)
5. Orbicularis oculi
- Origin: Medial wall of orbit
- Insertion: Circular path around margin of orbit
- Action: Closes eye; in the case of orbital part, forcefully closes an eye
6. Occipitofrontalis (frontal belly)
- Origin: Epicranial aponeurosis
- Insertion: Skin superior to supraorbital margin: Draws scalp anteriorly, raises eyebrows, and wrinkles skin of forehead horizontally as in look of surprise
Tortora, G. J., & Derrickson, B. H. (2017). Tortora’s Principles of Anatomy & Physiology. Wiley.