N3 Anatomy and Physiology AY 2023-2024

1. Platysma

Origin: originates from the fascia covering the superior chest (pectoralis major and deltoid muscles).

Insertion: inserts in the skin of the lower face and at the mouth’s corner, and mandible.

Action: it depresses the mandible, tenses the neck’s skin, and pulls down the lower lip.

2. Mentalis

Origin: originates from the mandible.

Insertion: inserts in the chin’s skin.

Action: it elevates and wrinkles the skin of the chin, which results in a protrusion or puckering of the chin. 

3. Orbicularis oris

Origin: originates from locations near the opening of the mouth.

Insertion: inserts in the skin at the mouth's corner.

Action: it puckers and closes the lips.

4. Corrugator supercilii

Origin: originates from the arch of the frontal bone, just above the nose bridge.

Insertion: inserts in the eyebrows’ skin.

Action: it vertically wrinkles the forehead’s skin and draws eyebrows inferiorly and medially.

5. Orbicularis oculi

Origin: originates from the orbit’s medial wall.

Insertion: inserts around the orbit.

Action: it allows the closing, blinking and squinting of the eyes.

6. Frontal belly 

Origin: originates from epicranial aponeurosis.

Insertion: inserts in the skin above the supraorbital margin.

Action: it raises the eyebrows and horizontally wrinkles the skin of the forehead.

REFERENCES:

Mallat, J., Marieb, E.N. & Wilhelm, P.B. (2016). Human anatomy (8th ed.). Washington, USA: Pearson.

Tortora, G.J. & Derrickson, B. (2017). Chapter 11: The Muscular System. In Principles of anatomy and physiology (15th ed.).