N3 Anatomy and Physiology AY 2023-2024

ACTIVITY 1

Name the muscle that may cause the following facial expression and write down its origin, insertion, and action.

1. 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. Mentalis

   • Origin: Mandible.

   • Insertion: Skin of chin

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

3. 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. 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. Orbicularis Oculi 

   • Origin: Medial wall of orbit. 

   • Insertion: Circular path around orbit 

   • Action: Closes eye 

6. Occipitofrontalis, frontal belly 

   • Origin: Epicranial aponeurosis. 

   • Insertion: Skin superior to supraorbital margin.

   • Action: Draws scalp anteriorly, raises eyebrows, and wrinkles skin of forehead horizontally as in look of surprise. 

Reference:

Tortora, G. J., & Derrickson, B. (2017). Principles of anatomy and physiology. Wiley Custom Learning Solutions.