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Musculoskeletal Concepts

Musculoskeletal Concepts. Dr. Suzan Ayers Western Michigan University. Lecture Overview. Bone functions & structure Joint classification and functions Muscle structure & function/contractions Synergistic/Antagonistic muscle roles Components of muscular fitness. Bone Functions.

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Musculoskeletal Concepts

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  1. Musculoskeletal Concepts Dr. Suzan Ayers Western Michigan University

  2. Lecture Overview • Bone functions & structure • Joint classification and functions • Muscle structure & function/contractions • Synergistic/Antagonistic muscle roles • Components of muscular fitness

  3. Bone Functions • Mechanical functions • Support for weight bearing • Protect internal organs • Sites for muscle attachment • Physiological functions • Heal/Maintain integrity • Store essential minerals (i.e., calcium, phosphate) • Immune system (marrow produces blood cells)

  4. Bone Structure • Composition • Calcium and phosphorous • Collagen: toughness, flexibility (1/3) • Calcium salts: hardness, rigidity (2/3)

  5. Bone Structure • Bone cells • Osteocytes (mature bone cells) • Osteoblasts (build bone) • Osteoclasts (remodel bone) • Bone types (1° difference isorganization) • Spongy: irregular latticework; releases Ca easier, more like a trampoline • Compact: concentric ring structure; provides protection/support; more like concrete • Factors influencing bone composition • Bone shape (femur vs. vertebra) • Function (skull vs. foot bones)

  6. Pg. 18-21: Bony Architecture Relative to Functions

  7. Joint Classifications Synovial • Joint cavity; bones joined by articular capsule and often ligaments; most familiar major joints (knee, ankle) • Articular cartilage • Joint capsule • Synovial membrane (lubrication, protection, nutrition) • Ligaments (major source of joint stability) • Ball and socket: circular motion (hip, shoulder) • Hinge: back & forth motion (ankle, knee, elbow) • Biaxial/Saddle: motion in 2 planes (knuckles)

  8. Joint Functions • Movement planes • Sagittal/Longitudinal run (vertical: left/right) • Flexion (angle decreases) • Extension (angle increases) • Coronal/Frontaljjax (vertical: front/back) • Transverseswing bat • (horizontal: top/bottom)

  9. Muscular Structure • Muscles cross bones • Muscle-tendon unit • bone-tendon-muscle-tendon-bone • Relationship between direction of muscular pull and joint axis of rotation determines resulting joint action

  10. Smooth muscle (digestive system, blood vessels) • Cardiac muscle • Skeletal muscle (p. 26) • Cells are elongated w/ many nuclei, ergo fibers • Actin(thin) & myosin(thick) create striated appearance • Motor unit: a nerve & associated muscle fibers • 5 main properties of muscle • Excitability from neural stimulation • Contractility in response to neural stimulation • Conductivity of electrical signals to coordinate motion • Extensibility shape distortion • Elasticity return to original shape

  11. Muscular Function/Contractions • Muscular contraction (pull only, no push): • cock-connect-pull-release (cross-bridge cycling) • http://www.sci.sdsu.edu/movies/actin_myosin_gif.html • Calcium essential for muscular contraction • Types of contractions • Concentric (shortening): produce movement • Eccentric (lengthening): control movement • Isometric (same length): maintain posture/stability • Isokinetic (same speed) • Isotonic (same tension) • Speed of movement: 2-1-4 (conc/ecc relationship)

  12. Muscle types relative to joint actions • Monoarticular (muscle crosses one joint brachialis) • Biarticular (muscle crosses 2 joints hamstring) • Polyarticular (muscle crosses >2 joints forearm) • Muscular contraction produces all joint actions of which it is capable • Limitations to ROM • Joint capsule tension on stretching side of joint • Flexibility of associated muscles/tendons • Soft tissues on compressed side of joint • Proximity/Contact of bony parts forming joint

  13. Synergistic/Antagonistic Roles • Synergistic • Contributing to desired motion, often by stabilization • Antagonistic • Opposing desired motion • Examples of each • Biceps: deltoids (s), triceps (a) • Pectoralis: triceps (s), lats (a) • Quadriceps: gluteals (s), hamstrings (a) • Role of synergistic/antagonistic muscle groups • Need for appropriate training sequence

  14. Little Ditties About Muscular Fitness • Motor unit • Motor nerve & all muscle fibers it innervates • Contractile force • Depends on # & size of motor units recruited • Table 4.1 (Sharkey, p. 46) • Slow-twitch/-oxidative (SO) • Fast-oxidative glycolytic (FOG) • Fast-glycolytic (FG) • SO recruited first, then FOG then FG(size principle) • DOMS • Micro-tears, edema, inflammation, enzyme leakage

  15. Components of Muscular Fitness • Strength • Max force exerted in 1 effort • Unrelated to fiber type • Fiber type differences based on rate of force production • Power • Strength x speed • Muscular Endurance • Ability to sustain sub-maximal contractions • Small not large muscle groups (more CV endurance)

  16. Power Endurance • Repeated performance of a skill w/ adequate speed • Reaction Time • Time between stimulus & response (processing & signaling) • Quickness • How an athlete reacts within a small area • Combination of reaction time & speed of movement • Has learned, trained and genetic components • Speed • Final product of reaction time & quickness

  17. Balance • Maintenance of equilibrium (dynamic or static) • Flexibility • ROM through which joints move • Influenced by gender, habitual use and stretching of joint and associated structures • Sport-specific & inversely related to joint stability • Agility • Rapid change of speed & direction while ↔ balance

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