Activity 1
Platysma
Origin: Fascia over deltoid and pectoralis major muscles.
Insertion: Skin superior to supraorbital margin.
Action: Draws scalp anteriorly, raises eyebrows, and wrinkles the skin of the forehead horizontally as in look of surprise.
Mentalis
Origin: Mandible.
Insertion: Skin of chin
Action: Elevates and protrudes lower lip and pulls skin of chin up, as in pouting.
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.
Corrugator Supercilii
Origin: Medial end of superciliary arch of frontal bone.
Insertion: Skin of eyebrow.
Action: Draws eyebrow inferiorly and wrinkles skin of the forehead vertically as in frowning.
Orbicularis Oculi
Origin: Medial wall of orbit.
Insertion: Circular path around orbit.
Action: Closes eye.
Occipitofrontalis (Frontal belly)
Origin: Epicranial Aponeurosis
Insertion: Skin superior to supraorbital margin.
Action: Draws scalp anteriorly, raises eyebrows, and wrinkles the skin of the forehead horizontally as in look of surprise.
References:
Tortora, G. J., & Derrickson, B. H. (2017). Principles of Anatomy & Physiology. Wiley.