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Muscle Origins, Insertions, and Actions

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  • Origin of Orbicularis oculi
    The frontal bone and maxilla.
  • Insertion of Orbicularis oculi
    The skin around the eyes.
  • Action of Orbicularis oculi
    Opens and closes the eyelids.
  • Origin of Orbicularis oris
    The maxilla and the mandible.
  • Insertion of Orbicularis oris
    The skin around the lips.
  • Action of Orbicularis oris
    Opens and closes the mouth.
  • Origin of Masseter
    The zygomatic arch.
  • Insertion of Masseter
    The mandibular ramus.
  • Action of Masseter
    Elevates the jaw.
  • Origin of Sternocleidomastoid
    The manubrium and clavicle.
  • Insertion of Sternocleidomastoid
    The mastoid process.
  • Action of Sternocleidomastoid
    Flexes and laterally turns the head.
  • Origin of External Intercostals
    The inferior part of the superior rib.
  • Insertion of External Intercostals
    The superior part of the inferior rib.
  • Action of External Intercostals
    Allows the rib cage to expand when you inhale.
  • Origin of Internal Intercostals
    The superior part of the inferior rib.
  • Insertion of Internal Intercostals
    The inferior part of the superior rib.
  • Action of Internal Intercostals
    Depresses the rib cage when you exhale.
  • Origin of Rectus Abdominis
    The pubic symphysis.
  • Insertion of Rectus Abdominis
    The xiphoid process and costal cartilage.
  • Action of Rectus Abdominis
    Flexes and rotates the lumbar spine.
  • Origin of External Oblique
    The lower 8 ribs.
  • Insertion of External Oblique
    The linea alba.
  • Action of External Oblique
    Trunk rotation.
  • Origin of Serratus Anterior
    Ribs 1-8.
  • Insertion of Serratus Anterior
    The medial border of scapula.
  • Action of Serratus Anterior
    Rotates the scapula.
  • Origin of Pectoralis Major
    The clavicle and sternum.
  • Insertion of Pectoralis Major
    The greater tubercle of humerus.
  • Action of Pectoralis Major
    Flexes, adducts, and medially rotates the arm.
  • Origin of Trapezius
    The occipital bone and vertebrae C7-T12.
  • Insertion of Trapezius
    The acromion process and scapular spine.
  • Action of Trapezius
    Raises, retracts, and rotates the scapular spine.
  • Origin of Latissimus Dorsi
    Thoracic and lumbar vertebrae, ribs, and iliac crest.
  • Insertion of Latissimus Dorsi
    The proximal humerus.
  • Action of Latissimus Dorsi
    Extends, adducts, and medially rotates the arm.
  • Origin of Gluteus Maximus
    The sacrum, coccyx, and ilium.
  • Insertion of Gluteus Maximus
    The iliotibial tract.
  • Action of Gluteus Maximus
    Extends the thigh.