1. Muscle: Platysma
Origin: Skin/fascia over deltoid and pectoralis major muscles
Insertion: Lower border of 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
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Originates from the incisive fossa of the mandible.
Insertion: Skin of chin (Mentolabial sulcus)
Action: Elevates, everts, and protrudes lower lip, and pulls skin of chin up, as in pouting
3. Muscle: Orbicularis Oris
Origin: Muscle fibers surrounding the opening of mouth
Insertion: Skin at corner of mouth
Action: Closes and protrudes lips, as in kissing; compresses lips against teeth; shapes lips during speech
4. Muscle: Corrugator Supercilii (Latin: wrinkler of the eyebrows)
Origin: Medial end of superciliary arch of frontal bone
Insertion: Skin of eyebrow
Action: The corrugator muscle draws the eyebrow downward and medially, producing the vertical wrinkles of the forehead.
5. Muscle: Orbicularis Oculi
Origin: Medial wall of orbit
Insertion: Circular path around orbit
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Skin of orbital region, lateral palpebral raphe, superior and inferior tarsal plates
Action: Closes eye
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Orbital part: closes eyelids tightly
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Palpebral part:closes eyelids gently
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Deep palpebral part: compresses lacrimal sac
6. Muscle: Occipitofrontalis (Frontalis)
Origin: Epicranial aponeurosis
Insertion: Skin superior to supraorbital margin
Action: Draws scalp anteriorly, raises eyebrows, and wrinkles skin of forehead
Reference:
Tortora, G. J., & Derrickson, B. H. (2017). Tortora’s Principles of Anatomy & Physiology. Wiley.