1. Musculoskeletal Concepts Dr. Suzan Ayers Western Michigan University

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

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

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

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

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 (contains synovial fluid)  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 (thumb)

8. Joint Functions Movement planes Movement planes –Sagittal/Longitudinal (vertical plane dividing L/R)  Flexion (angle decreases)  Extension (angle increases) –Coronal/Frontal (vertical plane dividing front/back) –Transverse (horizontal plane dividing top/bottom)

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

10. Smooth muscle (digestive system, blood vessels) Smooth muscle (digestive system, blood vessels) Cardiac muscle Cardiac muscle Skeletal muscle (p. 26) 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 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) : Muscular contraction (pull only, no push) : –cock-connect-pull-release (cross-bridge cycling) –http://www.sci.sdsu.edu/movies/actin_myosin_gif.html http://www.sci.sdsu.edu/movies/actin_myosin_gif.html Calcium essential for muscular contraction Calcium essential for muscular contraction Types of contractions 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) Speed of movement: 2-1-4 (conc/ecc relationship)

12. Muscle types relative to joint actions 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 Muscular contraction produces all joint actions of which it is capable Limitations to ROM 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 Synergistic –Contributing to desired motion, often by stabilization Antagonistic Antagonistic –Opposing desired motion Examples of each Examples of each –Biceps: deltoids (s), triceps (a) –Pectoralis: triceps (s), lats (a) –Quadriceps: gluteals (s), hamstrings (a) Role of synergistic/antagonistic muscle groups Role of synergistic/antagonistic muscle groups Need for appropriate training sequence Need for appropriate training sequence

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

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

16. Balance Balance –Maintenance of equilibrium (dynamic or static) Flexibility 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 Agility –Rapid change of speed & direction while ↔ balance