ACTIVITY 1:
1. Muscle: Platysma
Origin: Fascia over deltoid and pectoralis major muscle
Insertion: Mandible, blends with muscles around angle of mouth, and skin of lower face
Action: Draws outer part of lower lip inferiorly and posteriorly as in pouting; depresses mandible
2. Muscle: Mentalis
Origin: Mandible
Insertion: Skin of chin
Action: Elevates and protrudes lower lip and pulls skin of chin up, as in pouting
3. Muscle: Orbicularis Oris
Origin: Muscle fibers surrounding opening of mouth
Insertion: Skin at corner of mouth
Action: Closes and protrudes lips, as in kissing; compresses lips against teeth; and shapes lips during speech
4. Muscle: Corrugator Supercilii
Origin: Medial end of superciliary arch of frontal bone
Insertion: Skin of eyebrow
Action: Draws eyebrows inferiorly and wrinkles skin of forehead vertically as in frowning
5. Muscle: Orbicularis Oculi
Origin: Medial wall of orbit
Insertion: Circular path around orbit
Action: Closes eyes
6. Muscle: Occipitofrontalis (frontal belly)
Origin: Epicranial aponeurosis
Insertion: Skin superior to supraorbital margin
Action: Draws scalp anteriorly, raises eyebrows, and wrinkles skin of forehead horizontally as in look of surprise
Reference: Tortora, G. J., & Derrickson, B. (2017). Chapter 11: The Muscular System. Principles of Anatomy & Physiology (15th ed). John Wiley & Sons, Inc.