1. Platysma
Origin: arises from the fascia of the upper chest and shoulder muscles
Insertion: inserts into the lower border of the mandible (jawbone) and the skin and muscles of the lower face, around the mouth
Action: pulls the corners of the mouth downward, resulting in the downward pull of the lower lip
2. Mentalis
Origin: from the mental tubercle of the mandible — bony prominence on the mandible’s anterior surface, close to the midline of the chin
Insertion: inserts downward and medially into the skin of the chin
Action: contraction allows the upward and forward pulling of the chin, causing the lower lips to push outward
3. Orbicularis Oris
Origin: there is no distinct bony origin however, the fibers of this muscle surround the mouth
Insertion: inserts into various structures around the lips, including the skin and mucus membranes of the lips
Action: contraction brings the lips together therefore allowing lip closure and puckering of the lips
4. Corrugator Suprecilli
Origin: middle part of the superciliary arch (eyebrow ridge) of the frontal bone
Insertion: inserts into the forehead, middle of the eyebrows
Action: contraction results to pulling the inner ends of the eyebrows thus, forming vertical wrinkles in between
5. Orbicularis Oculi
Origin: no definite origin; arises from various points around the bones that houses the eyes
Insertion: inserts into several structures around the eye, including the skin of the eyelids
Action: allows the opening and closing of the eyes as its contraction results in the regulation of the eye opening
6. Occipitofrontalis
Origin: frontalis muscle from the connective tissue at the top of the skull and occipitalis muscle that originates from the base of the skull
Insertion: inserts into the skin of the forehead and eyebrow region
Action: frontalis muscle raises the eyebrows and horizontally wrinkles the skin while occipitalis muscle retracts the scalp backwards