Activity 1
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: Draws outer part of lower lip inferiorly and posteriorly 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 and protrudes lips, as in kissing; compresses lips against teeth; and shapes lips during speech
4. Corrugator Supercilii
Origin: Medial end of superciliary arch of frontal bone
Insertion: Skin of eyebrow.
Action: Draws eyebrow inferiorly and wrinkles skin of forehead vertically as in frowning
5. Orbicularis Oculi
Origin: Medial wall of orbit
Insertion: Circular path around orbit
Action: Closes eye
6. Occipitofrontalis
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. & Derrickson, B. (2017). The Muscular System. Principles of Anatomy and Physiology (15th ed.). Wiley.