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Muscular System - Anatomy & Physiology

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Terms in this set (29)

  • Origin vs Insertion of a muscle

    Origin is the fixed attachment point of a muscle, usually proximal. Insertion is the movable attachment point, usually distal.

  • Four basic fascicle arrangements in skeletal muscles

    Parallel, Pennate (uni-, bi-, multi-), Convergent, Circular.

  • Prime mover (agonist) muscle function

    The muscle that provides the major force for a specific movement.

  • Antagonist muscle function

    Muscle that opposes or reverses a prime mover's action; controls movement rate and prevents overshoot.

  • Synergist muscle function

    Muscles that assist the prime mover by promoting the same movement, reducing unwanted movements, or stabilizing joints.

  • Naming skeletal muscles by location

    Named after the bone or body region they are associated with, e.g., temporalis, intercostal.

  • Naming skeletal muscles by shape

    Named for their shape, e.g., deltoid (triangular), trapezius (trapezoid).

  • Muscle naming by relative size

    Terms like maximus, minimus, longus, brevis indicate muscle size, e.g., gluteus maximus.

  • Muscle naming by fiber direction

    Names indicate fiber orientation, e.g., rectus (straight), transversus, oblique.

  • Muscle naming by number of origins

    Names reflect number of heads or origins, e.g., biceps, triceps, quadriceps.

  • Muscle naming by origin and insertion

    Names include both origin and insertion points, e.g., sternocleidomastoid.

  • Muscle naming by action

    Names describe the muscle's action, e.g., flexor, extensor, adductor.

  • Epicranius muscle parts and function

    Frontal belly raises eyebrows and wrinkles forehead; occipital belly pulls scalp posteriorly.

  • Orbicularis oculi function

    Encircles the eye; produces blinking, squinting, and draws eyebrows down.

  • Zygomaticus muscle function

    Major and minor muscles that raise the corners of the mouth for smiling.

  • Orbicularis oris function

    Encircles the mouth; closes, purses, and protrudes lips.

  • Buccinator muscle function

    Compresses cheek; holds food between teeth during chewing; important in whistling and sucking.

  • Masseter muscle function

    Prime mover of jaw closure during chewing.

  • Temporalis muscle function

    Elevates and retracts mandible; maintains closed jaw at rest.

  • Sternocleidomastoid muscle actions

    Prime mover of head flexion; unilateral action rotates head to opposite side and tilts to same side.

  • Erector spinae muscle group function

    Prime mover of back extension; resists bending forward and helps return to erect posture.

  • External intercostals function

    Elevate ribs during inspiration to expand thoracic cavity.

  • Internal intercostals function

    Depress ribs during forced expiration to decrease thoracic volume.

  • Diaphragm function

    Dome-shaped muscle; prime mover of inspiration by increasing thoracic volume.

  • Rectus abdominis function

    Flexes lumbar vertebrae, stabilizes pelvis during walking, and depresses ribs.

  • External oblique muscle function

    Compresses abdomen, flexes and rotates vertebral column.

  • Levator ani muscle function

    Supports pelvic organs and forms a sling at anorectal junction; resists intra-abdominal pressure increases.

  • Pectoralis major muscle function

    Prime mover of arm adduction; medially rotates and assists in arm flexion.

  • Deltoid muscle function

    Prime mover of arm abduction; also involved in arm rotation, flexion, and extension.