N3 Anatomy and Physiology AY 2023-2024

1. Muscle: Platysma

   • Origin: Fascia over deltoid and pectoralis major muscles.

   • Insertion: 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

   • Insertion: Skin of Chin

   • Action: Elevates and protrudes lower lip and pulls skin of chin up, as in pouting.

3. Muscle: Orbicular 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.

4. Muscle: Corrugator supercilii

   • Origin: Medial end of superciliary arch of frontal bone.

   • Insertion: Skin of eyebrow

   • Action: Draws eyebrow inferiorly and wrinkles skin of forehead vertically as in frowning.

5. Muscle: Orbicularis oculi

   • Origin: Medial wall of orbit

   • Insertion: Circular path around orbit

   • Action: Closes eye

6. Muscle: Occipitofrontalis (Frontal belly)

   • 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. (2017). Principles of anatomy and physiology (15th ed.). Wiley Custom Learning Solutions.