Lecture Notes on Muscles of Facial Expression

Overview

• Facial Nerve (Cranial Nerve VII)
  • Innervates almost all muscles of facial expression.
  • Major branches: Temporal, Zygomatic, Buccal, Marginal, Cervical.

Muscles of Facial Expression

1. Occipitofrontalis (Epicranius)

• Components: Frontal belly and occipital belly.
• Origin: Epicranial aponeurosis.
• Insertion: Skin and subcutaneous tissue of the eyebrows and forehead.
• Action: Elevates eyebrows; wrinkles forehead (expression of surprise).

2. Orbicularis Oculi

• Origin: Medial orbital margin, medial palpebral ligament, lacrimal bone.
• Insertion: Skin around the orbit (eyelid).
• Action: Closes eyelids:
  • Palpebral part: Gentle closing.
  • Orbital part: Tight closing, winking.

3. Corrugator Superciliae

• Origin: Medial end of superciliary arch.
• Insertion: Skin superior to middle of the supraorbital margin and superciliary arch.
• Action: Draws eyebrows medially and inferiorly; vertical wrinkles above nose (concern or worry).

4. Procerus and Transverse Part of Nasalis

• Origin: Fascia covering nasal bone and lateral nasal cartilage.
• Insertion: Skin of the inferior forehead between eyebrows.
• Action: Depresses medial eyebrow; wrinkles skin over nose dorsum (dislike).

5. Levator Labi Superioris Alaeque Nasi

• Origin: Frontal process of maxilla, inferior medial orbit margin.
• Insertion: Major alar cartilage.
• Action: Depress alar laterally, dilate nostrils (anger).

6. Orbicularis Oris

• Origin: Medial maxilla and mandible, deep preoral skin.
• Insertion: Mucous membrane of lips.
• Action: Closes and protrudes lips (kissing); compresses lips (blowing).

7. Levator Labii Superioris and Zygomaticus Minor

• Origin:
  • Levator Labii Superioris: Infraorbital margin of maxilla.
  • Zygomaticus Minor: Anterior zygomatic bone.
• Insertion: Skin of upper lip.
• Action: Elevates upper lip, deepens nasolabial sulcus (sadness).

8. Buccinator

• Origin: Mandible alveolar processes, pterygomandibular raphe.
• Insertion: Angle of the mouth, orbicularis oris.
• Action: Presses cheek against teeth, works with tongue to keep food between occlusal surfaces, resists distension (blowing).

9. Zygomaticus Major

• Origin: Lateral zygomatic bone.
• Insertion: Angle of the mouth.
• Action: Elevates labial commissure (smiling, happiness).

10. Levator Anguli Oris

• Origin: Infraorbital maxilla.
• Insertion: Angle of the mouth.
• Action: Widens oral fissure (grinding).

11. Risorius and Depressor Anguli Oris

• Origin:
  • Risorius: Parotid fascia.
  • Depressor Anguli Oris: Anterolateral mandible base.
• Insertion: Angle of the mouth.
• Action: Depress labial commissure (frown, sadness).

12. Depressor Labi Inferioris

• Origin: Platysma, anterolateral mandible body.
• Insertion: Skin of lower lip.
• Action: Depresses lower lip (pouting, sadness).

13. Mentalis

• Origin: Mandible body.
• Insertion: Skin of chin.
• Action: Elevates, protrudes lower lip (doubt).

14. Platysma

• Origin: Subcutaneous tissue of infraclavicular and supraclavicular regions.
• Insertion: Base of mandible, cheek skin, lower lip, orbicularis oris.
• Action: Depresses mandible, tenses skin of inferior face/neck (tension, stress).

Conclusion

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