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Download Skeletal muscle action - Effingham County Schools
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Skeletal Muscle Action Origin and insertion • • • • The immovable fixed end of a muscle connects to a bone at the origin. The movable end of a muscle connects at the insertion. With contraction, insertion pulls toward the origin Can have more than one of each. Use and Disuse of Skeletal Muscles • Muscles increase with use = hypertrophy • Muscles decrease with disuse = atrophy (cast) Fast Twitch vs. Slow Twitch Muscle Fibers • Aerobic exercise uses slow twitch fibers – Ex. Swimming long distance, cross country skiingraises amount of ATP and blood flow to muscles. – Red fibers Fast twitch vs. Slow twitch muscle fibers • Anaerobic exercise uses fast twitch fibers. – Ex. Weightlifting, and sprinting diameter of muscle increases by producing more actin and myosin fibers. – White fibers Muscle Action of Head • Facial expression sadness, surprise, fear, disgust. – Zygomaticus mouth – Frontalis - eyebrow – Occipitalus eyebrow Muscle Action of Head • Mastication chewing – Masseter – Temporalis Closes jaw Muscle Action of Head Movement of Head • Sternocleidomastoid prayer position Muscle Action of the Pectoral Girdle (chest and shoulders) • • Associated with muscles that move arm Move scapula up, down, forward, and backward – – – Trapezius Serratus anterior Pectoralis minor Muscle action of the pectoral girdle (chest and shoulders) • • Associated with muscles that move arm Move scapula up, down, forward, and backward – – – Trapezius Serratus anterior Pectoralis minor Muscles that Move the Arm • Flexion - bending a joint to decrease the angle between bones. • Extension - movement increasing angles between parts in a joint • Abduction - movement of a body part away from the midline. • Rotation - movement turning a body part along its longitudinal axis. Muscles that move arm – Upper arm • Pectoralis major - flexor • Latissimus dorsi - extensor • Deltoid - abductor • Teres minor - rotator Muscles that move arm flexor extensor abductor rotator Lower Arm • • • • Biceps brachii - flexion Brachialis - flexion Brachioradialis - flexion Triceps brachii - extension flexion flexion flexion extension Muscle Action in Abdominal Wall (Six Pack) • Connect the rib cage to the pelvic girdle – – – • External oblique Internal oblique Rectus abdominus Hernia – – – A hole in the abdominal muscles. Intestines protrude outward to form a lump. Repaired by surgery Muscle Action in Thigh • – – Divided into anterior/posterior sections Anterior sections create flexion Posterior sections create extension, abduction, and rotation. • • • • Gluteus maximus Gluteus medius Tensor Fasciae Latae Adductors of the thigh Muscle Action in Thigh Cont… • – – Adduction - movement of a body part toward the midline. Adductor longus Gracilus Muscles that Move the Leg (Lower Leg) • Divided into two groups – Hamstring group are the flexors • • • • Biceps femoris Semitendenosus Semimembranosus Satorius – longest muscle in the body Muscles that Move the Leg (Lower Leg) • Divided into two groups – Quadriceps Group • • • Rectus femoris middle of the thigh Vastus lateralis outside of thigh Vastus medialis midline of thigh Longest Muscle in the Human Body • Sartorius
