1. Platysma
- Origin: Fascia over deltoid and pectoralis major muscles
- Insertion: Mandible, muscles around angle of mouth, and skin of lower face
- Action: Draws outer part of lower lip downward and backward as in pouting; depresses mandible
2. Mentalis
- Origin: Mandible
- Insertion: Skin of chin
- Action: Elevates and protrudes lower lip and pulls skin of chin up as in pouting
3. Orbicularis Oris
- Origin: Muscle fibers surrounding opening of mouth
- Insertion: Skin at corner of mouth
- Action: Closes lips, compresses lips against teeth, protrudes lips, and shapes lips during speech
4. Corrugator Supercilii
- Origin: Medial end of superciliary arch of frontal bone
- Insertion: Skin of eyebrow
- Action: Draws eyebrow downward as in frowning
5. Orbicularis Oculi
- Origin: Medial wall of orbit
- Insertion: Circular path around orbit
- Action: Closes eyes
6. Frontalis
- Origin: Galea aponeurotica
- Insertion: Skin superior to supraorbital margin
- Action: Draws scalp forward, raises eyebrows, and wrinkles skin of forehead horizontally
Reference: Tortora, G. J., & Grabowski, S. R. (1993). Principles of Anatomy and Physiology (7th ed.). HarperCollins College.