Activity 1
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Muscle: Platysma
Origin: The origin is fascia over deltoid and pectoralis major muscles.
Insertion: The insertion is at the mandible, blends with muscles around the angle of mouth, and skin of the lower face.
Action: The action Draws outer part of the lower lip inferiorly and posteriorly as in pouting; depresses the mandible.
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Muscle: Mentalis
Origin: The origin is at the mandible (anterior to roots of inferior incisors).
Insertion: The insertion is at the skin of the chin (mentolabial sulcus).
Action: The action is that it pulls the skin of the chin up, as in pouting (shows doubt).
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Muscle: Orbicularis Oris
Origin: The origin is at muscle fibers surrounding the opening of the mouth.
Insertion: The insertion is at the skin at the corner of the mouth.
Action: The action is that it closes and protrudes lips, as in kissing and compresses lips against teeth, and shapes lips during speech.
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Muscle: Corrugator Supercilii
Origin: The origin is at the medial end of the superciliary arch of the frontal bone.
Insertion: The insertion is at the skin of the eyebrow.
Action: The action is that it draws the eyebrow inferiorly and wrinkles the skin of the forehead vertically as in frowning.
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Muscle: Orbicularis Oculi
Origin: The origin is at the medial wall of orbit.
Insertion: The insertion is at the circular path around the orbit.
Action: The action is that it closes the eye.
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Muscle: Occipitofrontalis (frontal belly)
Origin: The origin is at the epicranial aponeurosis.
Insertion: The insertion is that the skin superior to supraorbital margin.
Action: The action is that it draws the scalp anteriorly, raises eyebrows, and wrinkles the skin of the forehead horizontally as in look of surprise.