Muscles of the face

Myology of the Face

1. Introduction

  • The face consists of numerous muscles, each with specific functions.

  • Facial muscles are organized into two layers: superficial and deep.

2. Contents

    1. Introduction

    1. Superficial plan: muscles of facial expression

    1. Deep plan: the muscles of mastication

    1. Supra-hyoid muscles

3. Superficial Plan: Muscles of Facial Expression

Overview

  • Muscles of facial expression enable various emotions.

  • They have a mobile part related to the facial skin (subcutaneous muscles).

  • Each muscle serves a specific function and generally features a thin structure with varied shapes.

Organization

  • Muscles of facial expression (MFE) are categorized into five regions:

    1. Epicranial

    2. Orbital

    3. Nasal

    4. Oral

    5. Facial

4. Muscles of Facial Expression

A. Epicranial Region

  • Occipito-frontalis Muscle:

    • Origin: Frontal belly from skin of the forehead, Occipital belly from the supreme nuchal line.

    • Attachment: Galea aponeurotica.

    • Innervation: Facial nerve.

    • Action: Moves the scalp.

    • Location: Temporo-frontal region.

  • Temporo-parietalis Muscle:

    • Origin: Galea aponeurotica.

    • Attachment: Auricular cartilage.

    • Innervation: Facial nerve.

    • Action: Pulls auricula cranially.

    • Location: Temporo-frontal region.

B. Orbital Region

  1. Orbicularis Oculi:

    • Parts: Palpebral, Lacrimal, Orbital.

    • Action:

      • Closes the eye / moves the eyebrows.

      • Closes eyelid.

      • Compresses lacrimal sac.

    • Innervation: Facial nerve.

  2. Corrugator Supercilii:

  • Origin: Nasal portion of the bone.

  • Attachment: Middle third of skin of the eyebrows and aponevrotic galea.

  • Innervation: Facial nerve.

  • Action: Depresses eyebrows and forehead.

C. Nasal Region

  1. Procerus:

    • Origin: Nasal bone and lateral nasal cartilage.

    • Attachment: Glabella skin.

    • Action: Depresses eyebrows and forehead.

    • Innervation: Facial nerve.

  2. Nasalis:

    • Parts: Transverse and Alar.

    • Actions:

      • Transverse part: Depresses nasal septum.

      • Alar part: Expansion of nostrils.

    • Innervation: Facial nerve.

  3. Depressor Septi Nasalis:

    • Origin: Alveolar eminence of the medial incisor.

    • Attachment: Greater alar cartilage and septal cartilage.

    • Innervation: Facial nerve.

    • Action: Depresses nasal septum.

  4. Levator Labii Superioris Alaeque Nasi:

    • Origin: Frontal process of maxillae.

    • Attachment: Wings of the nose and upper lip.

    • Innervation: Facial nerve.

    • Action: Elevates upper lip and wings of the nose.

D. Oral Region

  1. Orbicularis Oris:

    • Origin: Lateral to the angle of the mouth.

    • Attachment: Lips.

    • Action: Closes buccal opening and protrudes lips.

    • Innervation: Facial nerve.

  2. Depressor Anguli Oris:

    • Origin: Base of the mandible.

    • Attachment: Lips and labial commissure.

    • Action: Depresses labial commissure.

    • Innervation: Facial nerve.

  3. Mentalis:

    • Origin: Alveolar eminence of lower incisor.

    • Attachment: Skin of the chin.

    • Action: Elevates chin and protrudes lower lip.

    • Innervation: Facial nerve.

  4. Levator Anguli Oris:

    • Origin: Canine fossae.

    • Attachment: Angle of the mouth.

    • Action: Elevates labial commissure.

    • Innervation: Facial nerve.

  5. Zygomaticus Major:

    • Origin: Zygomatic bone.

    • Attachment: Upper lip and angle of the mouth.

    • Action: Elevates and abducts labial commissure.

    • Innervation: Facial nerve.

  6. Zygomaticus Minor:

    • Origin: Zygomatic bone.

    • Attachment: Upper lip and angle of the mouth.

    • Action: Levator and abductor of middle part of the mouth.

    • Innervation: Facial nerve.

  7. Depressor Labii Inferioris:

    • Origin: Base of the mandible.

    • Attachment: Lower lip.

    • Action: Depresses lower lip.

    • Innervation: Facial nerve.

5. Deep Plan: Muscles of Mastication

Introduction

  • Muscles are situated in the deep plane of the face and mobilize the mandible.

  • They are structurally robust to support mastication, described as having a pennate structure.

  • These muscles work together with the TMJ, teeth, and jaw bones comprising the masticatory system.

  • Formed by four muscles: masseter, temporalis, medial pterygoid, lateral pterygoid.

  • Blood Supply: Maxillary artery.

  • Nerve Supply: V3 branch of trigeminal nerve.

A. Masseter

  • Thick quadrilateral muscle with superficial and deep portions.

  • Origin:

    • Superficial part: maxillary process of zygomatic bone, anterior ⅔ of lower border of the zygomatic arch.

    • Deep part: posterior ⅓ of lower border and medial surface of zygomatic arch.

  • Attachment:

    • Superficial part: angle and lower ½ of lateral surface of the ramus of the mandible.

    • Deep part: upper ½ of lateral surface of the ramus mandible.

  • Innervation: V3: masseteric nerve.

  • Action:

    • Bilateral contraction: elevation and protraction of the mandible.

    • Unilateral contraction: moves the mandible ipsilaterally.

B. Temporalis

  • Broad triangular muscle located in the temporal fossa.

  • Origin: Temporal fossa.

  • Attachment: Coronoid process of the ramus.

  • Innervation: V3: deep temporal nerve.

  • Action: Elevation and retraction of the mandible.

C. Medial Pterygoid

  • Thick, quadrilateral muscle located in the infratemporal fossa.

  • Two heads: lateral and medial.

  • Origin: Pterygoid fossa and lateral lamina of the pterygoid process.

  • Attachment: Angle of the mandible.

  • Innervation: V3: medial pterygoid nerve.

  • Action:

    • Bilateral contraction: elevation and protraction of the mandible.

    • Unilateral contraction: moves the mandible contralaterally.

D. Lateral Pterygoid

  • Short, thick, conical muscle in the infratemporal fossa, with upper and lower heads.

  • Origin: Infratemporal crest and external surface of lateral lamina of pterygoid process.

  • Attachment: Articular disc and condylar process of the mandible.

  • Innervation: V3: lateral pterygoid nerve.

  • Action:

    • Bilateral contraction: initiates mandible opening and protraction.

    • Unilateral contraction: moves the mandible contralaterally.

6. Suprahyoid Muscles

Overview

  • A group of four muscles located superior to the hyoid bone, elevating the hyoid during swallowing.

  • Consists of: digastric, stylohyoid, geniohyoid, and mylohyoid.

  • All muscles insert on the hyoid bone.

A. Mylohyoid

  • Flat and triangular, forms the muscular floor of the mouth.

  • Origin: Mylohyoid line.

  • Attachment: Hyoid bone.

  • Innervation: Mylohyoid nerve (branch of V3).

  • Action: Supports and elevates the floor of the mouth.

B. Digastric

  • Small paired muscle with anterior and posterior bellies joined by an intermediate tendon.

  • Origin:

    • Anterior belly: digastric fossa of the mandible.

    • Posterior belly: mastoid process.

  • Attachment: Both bellies attach via intermediate tendon.

  • Innervation: Anterior belly: mylohyoid nerve, posterior belly: facial nerve.

  • Action: Elevates the hyoid and depresses the mandible.

C. Stylohyoid

  • Extends between temporal and hyoid bones.

  • Facilitates tongue retraction, swallowing, and keeps the airway open.

  • Origin: Styloid process.

  • Attachment: Hyoid bone.

  • Innervation: Facial nerve.

  • Action: Elevates hyoid bone in a posterosuperior direction.

D. Geniohyoid

  • Works with mylohyoid muscle as the floor of the mouth.

  • Origin: Inferior mental spine.

  • Attachment: Hyoid bone.

  • Innervation: C1 through hypoglossal nerve.

  • Action:

    • Fixes mandible: elevates and moves hyoid forward.

    • Fixed hyoid bone: elevates and retracts mandible.