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Principle Skeletal Muscles 1
Muscles of Facial Expression, Muscles that Move the Mandible and Muscles that Move the Eyeballs
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
OccipitofrontalisFront 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
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
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
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
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
Orbicularis Oculi
Origin – Medial wall of orbit Insertion – Circular path around orbit Action – Closes eye; wrinkles forehead
vertically
Levator Palpebrae Superioris
Origin – Roof of Orbit Insertion – Skin of upper eyelid Action - Opens Eye
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.
Masseter
Origin – Maxilla and Zygomatic Arch Insertion – Mandible Action – Elevates and retracts mandible
Temporalis
Origin – Temporal Bone Insertion – Mandible Action – Elevates and retracts mandible
Medial Pterigoid
Origin – Sphenoid bone and maxilla Insertion – Mandible Action – elevates and protracts mandible and
moves mandible from side to side
Lateral Pterygoid
Origin – Sphenoid Bone Insertion – TMJ Action – Protracts mandible, depresses
mandible and moves mandible from side to side
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.
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
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
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