Principle Skeletal Muscles 1

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Principle Skeletal Muscles 1

• Muscles of Facial Expression, Muscles that Move
  the Mandible and Muscles that Move the Eyeballs

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Muscles of Facial Expression

• The muscles of facial expression provide humans
  with the ability to express a wide variety of
  emotions. The muscles themselves lie within the
  layers of superficial fascia. The origins are
  generally in the fascia or bones of the skull and
  insertions into the skin of the face

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Occipitofrontalis Front and Occipital Bellies

• Front Belly
• Origin Epicranial Aponeurosis
• Insertion Skin superior to orbit
• Action Draws scalp forward, raises eyebrows and
  wrinkles skin of forehead horizontally
• Occipital Belly
• Origin Occipital and Temporal Bones
• Insertion Epicranial Aponeurosis
• Action Draws scalp backwards

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Orbicularis Oris

• Origin muscle fibers surrounding opening of
  mouth
• Insertion Skin at corner of mouth
• Action Closes and protrudes lips, compresses
  lips against teeth and shapes lips during speech

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Zygomaticus Major

• Origin zygomatic bone
• Insertion Skin at angle of mouth and
  orbicularis oris
• Action Draws corners of mouth outward and
  upward as in smiling

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Buccinator

• Origin Maxilla and Mandible
• Insertion Orbicularis Oris
• Action presses cheeks against teeth and lips,
  as in whistling draws corner of mouth laterally,
  assists in chewing be keeping food between teeth

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Platysma

• Origin Fascia over deltoid and pectoralis major
  muscles
• Insertion Mandible, muscles around mouth and
  skin of lower face
• Action Draws outer part of lower lip downward
  and backward as in pouting depresses mandible

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Orbicularis Oculi

• Origin Medial wall of orbit
• Insertion Circular path around orbit
• Action Closes eye wrinkles forehead vertically

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Levator Palpebrae Superioris

• Origin Roof of Orbit
• Insertion Skin of upper eyelid
• Action - Opens Eye

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Muscles that Move the Mandible

• Also known as muscles of mastication because
  they are used for biting and chewing. These
  muscles also assist in speech.

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Masseter

• Origin Maxilla and Zygomatic Arch
• Insertion Mandible
• Action Elevates and retracts mandible

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Temporalis

• Origin Temporal Bone
• Insertion Mandible
• Action Elevates and retracts mandible

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Medial Pterigoid

• Origin Sphenoid bone and maxilla
• Insertion Mandible
• Action elevates and protracts mandible and
  moves mandible from side to side

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Lateral Pterygoid

• Origin Sphenoid Bone
• Insertion TMJ
• Action Protracts mandible, depresses mandible
  and moves mandible from side to side

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Muscles that Move the Eyeballs

• Movement of the eyeballs are controlled by three
  pairs of extrinsic muscles. These are among the
  fastest contracting and most precisely controlled
  skeletal muscles of the body.

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Superior Rectus/Inferior Rectus

• Superior
• Origin Tendinous ring attached to bony orbit
  around the optic foramen
• Insertion Superior and central part of the
  eyeball
• Action Moves eyeball upward and medially and
  rotates its medially
• Inferior
• Origin - Tendinous ring attached to bony orbit
  around the optic foramen
• Insertion Inferior and central part of the
  eyeball
• Action Moves eyeball downward and medially and
  rotates it laterally

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Lateral/Medial Rectus

• Lateral
• Origin Tendinous ring attached to bony orbit
  around the optic foramen
• Insertion Lateral Side of Eyeball
• Action Moves eyeball laterally
• Medial
• Origin Tendinous ring attached to bony orbit
  around the optic foramen
• Insertion Medial Side of Eyeball
• Action Moves eyeball medially

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Superior/Inferior Oblique

• Superior
• Origin Tendinous ring attached to bony orbit
  around the optic foramen
• Insertion Eyeball between superior and lateral
  recti
• Action moves eyeball downward, laterally and
  rotates medially
• Inferior
• Origin Maxilla
• Insertion eyeball between inferior and lateral
  recti
• Action moves eyeball upward and laterally and
  rotates it laterally

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