Structure and Function of Muscle

Structure and Function of Muscle - KINESIOLOGY KINESIOLOGY...

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Unformatted text preview: KINESIOLOGY KINESIOLOGY STRUCTURE AND FUNCTION OF MUSCLE MUSCLE STRUCTURE AND FUNCTION Types of Muscle: Types • Smooth • Cardiac • Skeletal Skeletal Muscle Functions: • Movement • Stabilization • Thermogenesis MUSCLE COMPARTMENTS MUSCLE Compartments define Compartments functional groups of muscles: functional • Encased by a fascia Encased • Innervated by same nerve Innervated (usually) (usually) Compartmental syndrome EPIMYSIUM EPIMYSIUM PERIMYSIUM ENDOMYSIUM FASICLE BLOOD SUPPLY FIBER NEURAL SUPPLY SKELETAL MUSCLE SKELETAL STRUCTURE STRUCTURE Perimysium Perimysium Endomysium Muscle Fibers MUSCLE FUNCTIONS MUSCLE Prime Mover The muscles primarily responsible for producing a movement. Agonists The muscles primarily responsible for producing a movement. Stabilizers Muscles used to stabilize a joint segment of muscle attachment. Secondary Mover The muscles that assist the prime mover in producing a movement. Agonists The muscles that oppose or cause the opposite movement. Neutralizers Muscles that eliminate an unwanted movement. Synergists, two muscles that cause different movements but when contracted simultaneously, they cause a third, different movement. MUSCLE CONTRACTION TYPES MUSCLE Isometric: No change (iso) in length (metric) No change in joint angle Isokinetic: No change (iso) in velocity (kinetics) No change in joint angle velocity Isotonic: No change (iso) in force (tonic) No change in load moved BIARTICULATE MUSCLES BIARTICULATE Active Insufficiency: Inability to shorten enough to allow full range of motion in both joints Passive Insufficiency: Inability to lengthen enough to allow full range of motion in both joints (i.e. flexibility) MUSCLE ARCHITECTURE AND ITS EFFECTS ON FORCE MUSCLE FORCE ∝ CSA •Anatomic CSA ⊥ To longitudinal axis of muscle •Physiologic CSA ⊥ To longitudinal axis of the fibers BENEFITS OF MUSCLE FIBER PENNATION M1 (fusiform) M2 (penniform) PCSA1 Volume Volume CSA M1 = M 2 M1 = M 2 M1 = M 2 M1 < M 2 Mass CSA PCSA CSA = PCSA PCSA2 FIBER LENGTH : MUSCLE LENGTH FIBER SOL MG Posterior Lower Leg VL Quadriceps Hamstrings Muscle PCSA FL ML ML Increasing Force → VI SM PL RF TA EDL SAR VM BF FL ST Fiber Length Increasing Excursion → Trade off: Force for speed and ROM VARIATIONS IN FORCE AND MUSCLE LENGTH 120 100 80 Torque (%) 60 40 20 0 KNEE EXTENSION 70 90 110 130 Joint Angle (°) 150 170 190 Skeletal Muscle Length – Tension Relationship 5 4 3 2 1 1.0 Relative Force 0.8 0.6 0.4 0.2 0.0 1 2 3 Sarcome re Length (µm) 4 Z-Line 3.65µm 1 Z-Line 2.25µm 2 5 1.27µm VARIATIONS IN FORCE AND SHORTENING VELOCITY 120 100 Torque (%) KNEE EXTENSION 80 60 40 20 0 0 100 200 <50% Fast >50% Fast 300 400 500 Velocity (° per sec) POWER OUTPUT Power = Force * Velocity KNEE EXTENSION 250 200 >50% Fast Power (T * v) 150 100 50 0 0 100 200 <50% Fast 300 400 500 Velocity (°/sec) Skeletal Muscle Force-Velocity Relationship 600 500 400 Force (N) 300 200 100 0 -8 -6 -4 -2 Eccentric Isometric Concentric Po Power = F · v A.V. Hill Vmax 0 Velocity (m·s-1) 2 4 6 8 REGULATION OF FORCE REGULATION BIOMECHANICAL 1. 1. Angle of insertion Impulse MUSCULAR 1. Structural • Fiber arrangement • Physiologic CSA Functional • Force – Velocity • Length - Tension NEURAL 1. Voluntary • Motor Unit Recruitment (Size Principle) • Rate Coding Reflex • Excitatory • Inhibitory • Central Pattern Generator 1. 1. ...
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