Muscles of Facial Expression

Module 10.6: The Muscles of Facial Expression

Importance of Muscles of Facial Expression

  • The muscles of facial expression play a significant role in:
    • Eating: Facilitate the manipulation and consumption of food.
    • Communication: Allow for a range of expressions that convey emotions and intentions.

Origin and Insertion of Facial Expression Muscles

  • Most muscles of facial expression originate on the surface of the skull.
    • Exception: The platysma, located in the neck.
  • At their insertions, the fibers of the epimysium integrate with the superficial fascia (subcutaneous layer) and the dermis of the skin.
    • Consequence: When these muscles contract, they cause movement of the skin, enabling facial expressions.

Major Facial Muscles

  • Frontal Belly of Occipitofrontalis
  • Occipital Belly of Occipitofrontalis
  • Epicranial Aponeurosis: A collagenous sheet connecting the two bellies of the occipitofrontalis muscle.
Lateral View of Major Facial Muscles
  • Significant muscles involved in lip movements:
    • Orbicularis Oculi: Muscle encircling the eye responsible for closing the eyelids.
    • Zygomaticus Minor: Elevates the upper lip.
    • Zygomaticus Major: Responsible for smiling.
    • Risorius: Assists in retracting the corner of the mouth.
    • Orbicularis Oris: Encircles the mouth and is involved in actions such as kissing and whistling.
    • Bucinator: Pushes food between teeth while chewing.
    • Levator Labii Superioris: Elevates the upper lip.
    • Levator Anguli Oris: Elevates the angle of the mouth.
    • Depressor Labii Inferioris: Lowers the lower lip.
    • Depressor Anguli Oris: Lowers the angle of the mouth.
    • Mentalis: Raises and protrudes the lower lip (noted as cut in the diagram).
Anterior and Posterior Views of Muscles

  • Anterior View:

    • Shows superficial muscles on the right side of the face including the facial muscles listed.

  • Posterior View:

    • Depicts deeper muscles on the left side of the face.

Muscles Involved in Chewing and Movement

  • Temporalis: Important for elevating the jaw.
  • Masseter: Vital for closing the jaw during chewing.

Summary of Key Muscles around the Mouth and Cheek:

  • Levator Labii Superioris
  • Zygomaticus Minor
  • Zygomaticus Major
  • Buccinator
  • Orbicularis Oris
  • Risorius
  • Mentalis (cut)
  • Depressor Labii Inferioris
  • Temporalis
  • Masseter
  • Depressor Anguli Oris

Notable Functional Associations

  • The Buccinator muscle is involved in whistling due to its role in maintaining tension in the cheeks.

Diagrams Included

  • Lateral and anterior views highlighting muscle positions.
  • Separation between superficial and deeper muscles of the face clearly illustrated in diagrams, aiding in visual understanding of muscle anatomy.