ACTIVITY 1. Name the muscle that may cause the following facial expression and write down its origin, insertion and action.
- Platysma
- Origin. Fascia over deltoid and pectoralis major muscles.
- Insertion. The base of the mandible and skin of the lower face.
- Action. Draws the corners of the mouth, particularly lower lip, inferiorly and posteriorly as in pouting; depresses the lower jaw.
- Mentalis
- Origin. The mandible or lower jaw.
- Insertion. The skin of the chin.
- Action. Protrusion of the lower lip and elevation and wrinkling of the skin of the chin.
- Orbicularis oris
- Origin. Muscle fibers surrounding opening of mouth.
- Insertion. The skin surrounding the lips.
- Action. Puckers the lips, compresses them against teeth, shapes the lips during speech, and closes the mouth.
- Corrugator supercilii
- Origin. Medial end of superciliary arch of frontal bone.
- Insertion. The skin of the forehead near the eyebrow.
- Action. Drawing the eyebrows inferiorly and wrinkling the skin of the forehead vertically, as in frowning.
- Orbicularis oculi
- Origin. Medial wall of orbit.
- Insertion. Circular path around orbit.
- Action. Closes the eyes.
- Occipitofrontalis
- Origin.
- Frontal belly: Epicranial aponeurosis
- Occipital belly: Occipital bone and the mastoid process of the temporal bone
- Insertion.
- Frontal belly: Inserts into the skin superior to the supraorbital margin
- Occipital belly: Inserts into the epicranial aponeurosis
- Action.
- Frontal belly: Draws scalp posteriorly
- Occipital belly: Draws scalp anteriorly, raises eyebrows, and wrinkles skin of forehead horizontally as in look of surprise
- Origin.
Reference
Tortora, G., & Derrickson B. (2017). Principles of Anatomy and Physiology (15th ed.). Wiley.