musculoskeletal concepts
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Musculoskeletal ConceptsMusculoskeletal Concepts
Dr. Suzan AyersDr. Suzan AyersWestern Michigan UniversityWestern Michigan University
Lecture OverviewLecture Overview
Bone functions & structureBone functions & structure
Joint classification and functionsJoint classification and functions
Muscle structure & function/contractionsMuscle structure & function/contractions
Synergistic/Antagonistic muscle rolesSynergistic/Antagonistic muscle roles
Components of muscular fitnessComponents of muscular fitness
Bone FunctionsBone Functions
Mechanical functionsMechanical functions– Support for weight bearingSupport for weight bearing– Protect internal organsProtect internal organs– Sites for muscle attachmentSites for muscle attachment
Physiological functionsPhysiological functions– Heal/Maintain integrityHeal/Maintain integrity– Store essential minerals (i.e., calcium, Store essential minerals (i.e., calcium,
phosphate)phosphate)– Immune system (marrow produces blood cells)Immune system (marrow produces blood cells)
Bone StructureBone Structure CompositionComposition
– Calcium and phosphorous Calcium and phosphorous – Collagen: toughness, flexibility (1/3)Collagen: toughness, flexibility (1/3)– Calcium salts: hardness, rigidity (2/3)Calcium salts: hardness, rigidity (2/3)
Bone StructureBone Structure Bone cellsBone cells
– Osteocytes (mature bone cells)Osteocytes (mature bone cells)– Osteoblasts (build bone)Osteoblasts (build bone)– Osteoclasts (remodel bone)Osteoclasts (remodel bone)
Bone types Bone types ((1° difference is1° difference is organizationorganization))– SpongySpongy: irregular latticework; releases Ca : irregular latticework; releases Ca easier, more like a trampolineeasier, more like a trampoline– CompactCompact: concentric ring structure; provides : concentric ring structure; provides
protection/support; more like concreteprotection/support; more like concrete
Factors influencing bone compositionFactors influencing bone composition– Bone shape (femur vs. vertebra)Bone shape (femur vs. vertebra)– Function (skull vs. foot bones)Function (skull vs. foot bones)
Pg. 18-21: Bony Architecture Relative to Pg. 18-21: Bony Architecture Relative to FunctionsFunctions
Joint ClassificationsJoint Classifications
SynovialSynovial– Joint cavity; bones joined by articular capsule Joint cavity; bones joined by articular capsule
and often ligaments; most familiar major and often ligaments; most familiar major joints joints (knee, ankle)(knee, ankle)
Articular cartilageArticular cartilage Joint capsuleJoint capsule Synovial membrane (lubrication, protection, Synovial membrane (lubrication, protection,
nutrition)nutrition) Ligaments Ligaments (major source of joint stability)(major source of joint stability)
– Ball and socket: circular motion (hip, shoulder)Ball and socket: circular motion (hip, shoulder)– Hinge: back & forth motion (ankle, knee, Hinge: back & forth motion (ankle, knee,
elbow)elbow)– Biaxial/Saddle: motion in 2 planes (knuckles)Biaxial/Saddle: motion in 2 planes (knuckles)
Joint FunctionsJoint Functions Movement planesMovement planes
– Sagittal/Longitudinal Sagittal/Longitudinal runrun
(vertical: left/right)(vertical: left/right) Flexion (angle decreases)Flexion (angle decreases) Extension (angle increases)Extension (angle increases)
– Coronal/FrontalCoronal/Frontal jjaxjjax
(vertical: front/back)(vertical: front/back)
– TransverseTransverse swing batswing bat
– (horizontal: top/bottom)(horizontal: top/bottom)
Muscular StructureMuscular Structure Muscles cross bonesMuscles cross bones
Muscle-tendon unitMuscle-tendon unit– bone-tendon-muscle-tendon-bonebone-tendon-muscle-tendon-bone
Relationship between direction of Relationship between direction of muscular pull and joint axis of rotation muscular pull and joint axis of rotation determines resulting joint actiondetermines resulting joint action
Smooth muscle Smooth muscle (digestive system, blood vessels)(digestive system, blood vessels) Cardiac muscleCardiac muscle Skeletal muscle Skeletal muscle (p. 26)(p. 26)
– Cells are elongated w/ many nuclei, ergo fibersCells are elongated w/ many nuclei, ergo fibers– ActinActin(thin)(thin) & myosin & myosin(thick)(thick) create striated create striated
appearanceappearance– Motor unit: a nerve & associated muscle fibersMotor unit: a nerve & associated muscle fibers
5 main properties of muscle5 main properties of muscle– ExcitabilityExcitability from neural stimulation from neural stimulation– ContractilityContractility in response to neural stimulation in response to neural stimulation– Conductivity Conductivity of electrical signals to coordinate of electrical signals to coordinate
motionmotion– Extensibility Extensibility shape distortionshape distortion– Elasticity Elasticity return to original shapereturn to original shape
Muscular Function/ContractionsMuscular Function/Contractions Muscular contraction Muscular contraction (pull only, no push)(pull only, no push)::
– cock-connect-pull-release (cross-bridge cycling)cock-connect-pull-release (cross-bridge cycling)– http://www.sci.sdsu.edu/movies/actin_myosin_gif.html
Calcium essential for muscular contraction Calcium essential for muscular contraction Types of contractionsTypes of contractions
– ConcentricConcentric (shortening): produce movement (shortening): produce movement– EccentricEccentric (lengthening): control movement (lengthening): control movement– IsometricIsometric (same length): maintain (same length): maintain
posture/stabilityposture/stability– IsokineticIsokinetic (same speed) (same speed)– IsotonicIsotonic (same tension) (same tension)
Speed of movement: 2-1-4 Speed of movement: 2-1-4 (conc/ecc relationship)(conc/ecc relationship)
Muscle types relative to joint actionsMuscle types relative to joint actions– Monoarticular (muscle crosses one joint Monoarticular (muscle crosses one joint
brachialisbrachialis))– Biarticular (muscle crosses 2 joints Biarticular (muscle crosses 2 joints hamstringhamstring))– Polyarticular (muscle crosses >2 joints Polyarticular (muscle crosses >2 joints
forearmforearm)) Muscular contraction produces all joint Muscular contraction produces all joint
actions of which it is capableactions of which it is capable Limitations to ROMLimitations to ROM
– Joint capsule tension on stretching side of jointJoint capsule tension on stretching side of joint– Flexibility of associated muscles/tendonsFlexibility of associated muscles/tendons– Soft tissues on compressed side of jointSoft tissues on compressed side of joint– Proximity/Contact of bony parts forming jointProximity/Contact of bony parts forming joint
Synergistic/Antagonistic RolesSynergistic/Antagonistic Roles SynergisticSynergistic
– Contributing to desired motion, often by Contributing to desired motion, often by stabilizationstabilization
AntagonisticAntagonistic– Opposing desired motionOpposing desired motion
Examples of eachExamples of each– Biceps: deltoids (s), triceps (a)Biceps: deltoids (s), triceps (a)– Pectoralis: triceps (s), lats (a)Pectoralis: triceps (s), lats (a)– Quadriceps: gluteals (s), hamstrings (a)Quadriceps: gluteals (s), hamstrings (a)
Role of synergistic/antagonistic muscle Role of synergistic/antagonistic muscle groupsgroups
Need for appropriate training sequenceNeed for appropriate training sequence
Little Ditties About Muscular Little Ditties About Muscular FitnessFitness
Motor unitMotor unit– Motor nerve & all muscle fibers it innervatesMotor nerve & all muscle fibers it innervates
Contractile forceContractile force– Depends on # & size of motor units recruitedDepends on # & size of motor units recruited
Table 4.1 Table 4.1 (Sharkey, p. 46)(Sharkey, p. 46)
– Slow-twitch/-oxidative (SO)Slow-twitch/-oxidative (SO)– Fast-oxidative glycolytic (FOG)Fast-oxidative glycolytic (FOG)– Fast-glycolytic (FG)Fast-glycolytic (FG)– SO recruited first, then FOG then FGSO recruited first, then FOG then FG (size (size
principle)principle)
DOMSDOMS– Micro-tears, edema, inflammation, enzyme Micro-tears, edema, inflammation, enzyme
leakageleakage
Components of Muscular FitnessComponents of Muscular Fitness StrengthStrength
– Max force exerted in 1 effortMax force exerted in 1 effort– Unrelated to fiber typeUnrelated to fiber type– Fiber type differences based on rate of force Fiber type differences based on rate of force
productionproduction PowerPower
– Strength x speedStrength x speed Muscular EnduranceMuscular Endurance
– Ability to sustain sub-maximal contractionsAbility to sustain sub-maximal contractions– Small not large muscle groups (more CV Small not large muscle groups (more CV
endurance)endurance)
Power EndurancePower Endurance– Repeated performance of a skill w/ adequate Repeated performance of a skill w/ adequate
speedspeed
Reaction TimeReaction Time– Time between stimulus & response (processing & Time between stimulus & response (processing &
signaling)signaling)
QuicknessQuickness– How an athlete reacts within a small areaHow an athlete reacts within a small area– Combination of reaction time & speed of Combination of reaction time & speed of
movementmovement– Has learned, trained and genetic componentsHas learned, trained and genetic components
SpeedSpeed– Final product of reaction time & quicknessFinal product of reaction time & quickness
BalanceBalance– Maintenance of equilibrium (dynamic or static)Maintenance of equilibrium (dynamic or static)
FlexibilityFlexibility– ROM through which joints moveROM through which joints move– Influenced by gender, habitual use and Influenced by gender, habitual use and
stretching of joint and associated structuresstretching of joint and associated structures– Sport-specific & inversely related to joint Sport-specific & inversely related to joint
stabilitystability
AgilityAgility– Rapid change of speed & direction while Rapid change of speed & direction while ↔↔
balancebalance
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