chapter 2 neuromuscular fundamentals

Chapter 2 Chapter 2 Neuromuscular Neuromuscular FundamentalsFundamentals

Manual of Structural Kinesiology2-1

Skeletal MusclesSkeletal Muscles

Responsible for movement of body and all of its Responsible for movement of body and all of its jointsjoints

Muscle contraction produces force that causes Muscle contraction produces force that causes joint movementjoint movement

Muscles also provide Muscles also provide protectionprotection

posture and support posture and support

produce a major portion of total body heatproduce a major portion of total body heat

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Muscle NomenclatureMuscle Nomenclature

Muscles are usually named due toMuscles are usually named due to visual appearancevisual appearance anatomical locationanatomical location functionfunction

Shape – deltoid, rhomboidShape – deltoid, rhomboid

Size – gluteus maximus, teres minorSize – gluteus maximus, teres minor

Number of divisions – triceps brachiiNumber of divisions – triceps brachii

Direction of its fibers – external abdominal Direction of its fibers – external abdominal obliqueoblique

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Shape of Muscles & Fiber Shape of Muscles & Fiber ArrangementArrangement

Cross section diameterCross section diameter factor in musclefactor in muscle’’s ability to exert forces ability to exert force greater cross section diameter = greater force greater cross section diameter = greater force

exertionexertion

MuscleMuscle’’s ability to shortens ability to shorten longer muscles can shorten through a greater longer muscles can shorten through a greater

range range more effective in moving joints through large more effective in moving joints through large

ranges of motionranges of motion

Manual of Structural KinesiologyNeuromuscular Fundamentals 2-4

Muscle TerminologyMuscle Terminology OriginOrigin

Structurally, the proximal attachment of a muscle or the Structurally, the proximal attachment of a muscle or the part that attaches closest to the midline or center of the part that attaches closest to the midline or center of the bodybody

Functionally & historically, the least movable part or Functionally & historically, the least movable part or attachment of the muscleattachment of the muscle

InsertionInsertion Structurally, the distal attachment or the part Structurally, the distal attachment or the part

that attaches farthest from the midline or center that attaches farthest from the midline or center of the bodyof the body

Functionally & historically, the most movable part Functionally & historically, the most movable part is generally considered the insertionis generally considered the insertion

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Types of muscle Types of muscle contractioncontraction

Muscle contractions can be used to Muscle contractions can be used to causecause, , controlcontrol, or , or preventprevent joint movement or joint movement or to initiate or accelerate movement of a body to initiate or accelerate movement of a body

segmentsegment to slow down or decelerate movement of a body to slow down or decelerate movement of a body

segmentsegment to prevent movement of a body segment by to prevent movement of a body segment by

external forcesexternal forces

All muscle contractions are either isometric or All muscle contractions are either isometric or isotonicisotonic




Muscle ContractionMuscle Contraction(under tension)(under tension)

IsometricIsometric IsotonicIsotonic

EccentricEccentricConcentricConcentric

Preventing

Motion


Isometric contractionIsometric contraction active tension is developed active tension is developed

within muscle but joint angles within muscle but joint angles remain constantremain constant

static contractionsstatic contractions significant amount of tension significant amount of tension

may be developed in muscle may be developed in muscle to maintain joint angle in to maintain joint angle in relatively static or stable relatively static or stable positionposition

may be used to prevent a may be used to prevent a body segment from being body segment from being moved by external forcesmoved by external forces

preventing motionpreventing motion



Concentric contractions Concentric contractions involve muscle developing involve muscle developing active tension as it shortensactive tension as it shortens Causing motionCausing motion

Eccentric Eccentric contractions involvecontractions involvethe muscle the muscle lengthening under lengthening under active tensionactive tension Controlling motionControlling motion

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Role of MusclesRole of Muscles

Agonist Agonist musclesmuscles cause joint motion through a specified plane of motion when cause joint motion through a specified plane of motion when

contracting concentricallycontracting concentrically

known as primary or prime moversknown as primary or prime movers Some agonist muscles, because of their relative location,

size, length, or force generation capacity, are able to contribute significantly more to the joint movement than other agonists

Assisters or assistant movers Agonist muscles that contribute significantly less to the

joint motion

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AntagonistAntagonist musclesmuscles located on opposite side of a joint from the located on opposite side of a joint from the

agonistagonist have the opposite concentric actionhave the opposite concentric action known as contralateral musclesknown as contralateral muscles work in cooperation with agonist muscles work in cooperation with agonist muscles

by relaxing & allowing movementby relaxing & allowing movement when contracting concentrically perform when contracting concentrically perform

the opposite joint motion of agonistthe opposite joint motion of agonist Ex. Ex. quadriceps muscles are antagonists to

hamstrings in knee flexion

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StabilizersStabilizers surround joint or body partsurround joint or body part contract to fixate or stabilize the area to enable contract to fixate or stabilize the area to enable

another limb or body segment to exert force & moveanother limb or body segment to exert force & move known as fixatorsknown as fixators essential in establishing a relatively firm base for the essential in establishing a relatively firm base for the

more distal joints to work from when carrying out more distal joints to work from when carrying out movementsmovements

Ex. biceps curl muscles of scapula & glenohumeral joint must contract in

order to maintain shoulder complex & humerus in a relatively static position so that the biceps brachii can more effectively perform curls

Proximal stability is needed for distal mobility.

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SynergistSynergist assist in action of agonistsassist in action of agonists

not necessarily prime movers for the actionnot necessarily prime movers for the action

known as guiding musclesknown as guiding muscles

assist in refined movement & rule out undesired assist in refined movement & rule out undesired motionsmotions

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Force Couples Force couples occur

when two or more forces are pulling in different directions on an object, causing the object to rotate about its axis

Coupling of muscular forces together in the body can result in a more efficient movement

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Lines of PullLines of PullConsider the followingConsider the following

1.1. Exact locations of bony landmarks to which muscles attach Exact locations of bony landmarks to which muscles attach proximally & distally and their relationship to jointsproximally & distally and their relationship to joints

2.2. Planes of motion through which a joint is capable of Planes of motion through which a joint is capable of movingmoving

3.3. MuscleMuscle’’s relationship or line of pull relative to the joints relationship or line of pull relative to the joint ’’s s axes of rotationaxes of rotation

4.4. As a joint moves the line of pull may change & result in As a joint moves the line of pull may change & result in muscle having a different or opposite action than in the muscle having a different or opposite action than in the original positionoriginal position

5.5. Effect of a muscleEffect of a muscle’’s relative length on its ability to generate s relative length on its ability to generate forceforce

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Factors affecting muscle Factors affecting muscle tension developmenttension development

All or None PrincipleAll or None Principle - regardless of number, individual - regardless of number, individual muscle fibers within a given motor unit will either fire & muscle fibers within a given motor unit will either fire & contract maximally or not at allcontract maximally or not at all

Difference between lifting a minimal vs. maximal resistance Difference between lifting a minimal vs. maximal resistance is the number of muscle fibers recruitedis the number of muscle fibers recruited

The number of muscle fibers recruited may be increased The number of muscle fibers recruited may be increased byby activating those motor units containing a greater activating those motor units containing a greater

number of muscle fibersnumber of muscle fibers activating more motor unitsactivating more motor units increasing the frequency of motor unit activationincreasing the frequency of motor unit activation

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Motor ControlMotor Control A motor neuron and the muscle A motor neuron and the muscle

fibers it innervates.fibers it innervates.

Fine controlFine control small motor units contain as few small motor units contain as few

as as 20 muscle fibers per nerve fiber20 muscle fibers per nerve fiber

eye muscleseye muscles Allow for greater dexterity Allow for greater dexterity

because of a lower neuron to because of a lower neuron to muscle fiber ratio.muscle fiber ratio.

Gross controlGross control gastrocnemius muscle has 1000 gastrocnemius muscle has 1000

fibers per nerve fiberfibers per nerve fiber One motor neuron controls many One motor neuron controls many

muscle fibers which allows for muscle fibers which allows for strength production.strength production.

Recruitment and Stimulus Recruitment and Stimulus IntensityIntensity

Strength of muscle Strength of muscle contraction is dependant of contraction is dependant of # of motor units recruited# of motor units recruited

Multiple motor unit Multiple motor unit summationsummation The harder the activity is the The harder the activity is the

more motor units will be more motor units will be recruited. recruited. Lifting 1 lb vs. 100 lbsLifting 1 lb vs. 100 lbs

How do you explain the How do you explain the rapid strength gains when rapid strength gains when you first start training?you first start training?

All or None PrincipleAll or None Principle Typical muscle contractionTypical muscle contraction

The number of motor units The number of motor units responding (and number of responding (and number of muscle fibers contracting) muscle fibers contracting) within the muscle may vary within the muscle may vary significantly from relatively significantly from relatively few to virtually allfew to virtually all

depending on the number depending on the number of muscle fibers within each of muscle fibers within each activated motor unit & the activated motor unit & the number of motor units number of motor units activatedactivated

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Metabolism and Skeletal Muscle Fibers TypesMetabolism and Skeletal Muscle Fibers Types There are 3 different types skeletal muscle fibers based There are 3 different types skeletal muscle fibers based

histological differences, duration of a twitch and the method of histological differences, duration of a twitch and the method of ATP productionATP production

slow oxidative fibersslow oxidative fibers fast oxidative fibersfast oxidative fibers fast glycolytic fibersfast glycolytic fibers

Proportions genetically determinedProportions genetically determined

Fast Glycolytic, Fast-Twitch Fast Glycolytic, Fast-Twitch FibersFibers

Fast glycolytic, fast-twitch fibers:Fast glycolytic, fast-twitch fibers: rich in enzymes for phosphagen and glycogen-lactic rich in enzymes for phosphagen and glycogen-lactic

acid systemsacid systems Limited # of mitochondria and high concentration of Limited # of mitochondria and high concentration of

glycogen stores makes it adapted for anaerobic glycogen stores makes it adapted for anaerobic metabolismmetabolism a lack of myoglobin in glycolytic fibers results in a white colora lack of myoglobin in glycolytic fibers results in a white color

sarcoplasmic reticulum releases calcium quickly so sarcoplasmic reticulum releases calcium quickly so contractions are quicker which are required for contractions are quicker which are required for movements that produce speed and power.movements that produce speed and power. extraocular eye muscles, gastrocnemius and biceps brachiiextraocular eye muscles, gastrocnemius and biceps brachii

Slow- Twitch FibersSlow- Twitch Fibers

Slow oxidative, slow-twitch fibersSlow oxidative, slow-twitch fibers Oxidative fibers contain greater amounts of mitochondria Oxidative fibers contain greater amounts of mitochondria

and myoglobin which binds oxygen.and myoglobin which binds oxygen. Rich blood supply and high concentration of myoglobin Rich blood supply and high concentration of myoglobin

these fibers appear red in color. these fibers appear red in color. adapted for endurance (resistant to fatigue)adapted for endurance (resistant to fatigue)

Soleus and postural muscles of the back are predominantly Soleus and postural muscles of the back are predominantly this type.this type.

Fast Oxidative FibersFast Oxidative Fibers

Fast oxidative fibersFast oxidative fibers: : characteristics of both fast and slow fibers.characteristics of both fast and slow fibers. have a fast twitch (use ATP quickly)have a fast twitch (use ATP quickly) Increased mitochondria make it moderately Increased mitochondria make it moderately

resistant to fatigue resistant to fatigue Usually make up 10% of fibers.Usually make up 10% of fibers.

Training will make these fibers adapt Training will make these fibers adapt to become functionally more fast or to become functionally more fast or slowslow. .

Cellular Adaptations to Cellular Adaptations to Physical DemandsPhysical Demands

Strength training: high intensity training stresses Strength training: high intensity training stresses anaerobic pathways.anaerobic pathways. Increased # and size of glycolytic associated Increased # and size of glycolytic associated

enzymes and substrates enzymes and substrates ATP, creatine phosphate and glycogenATP, creatine phosphate and glycogen

Endurance training: Enhance the aerobic Endurance training: Enhance the aerobic pathways. pathways. increased # and size of mitochondrial membranes increased # and size of mitochondrial membranes

and associated enzymes. and associated enzymes. This will increase OThis will increase O2 2 uptake ( VOuptake ( VO2 max2 max) which will delay ) which will delay

the formation of lactic acid. the formation of lactic acid.

Factors affecting muscle Factors affecting muscle tension developmenttension development

Number of muscle fibers per motor unit varies Number of muscle fibers per motor unit varies significantlysignificantly From less than 10 in muscles requiring precise and From less than 10 in muscles requiring precise and

detailed such as muscles of the eyedetailed such as muscles of the eye

To as many as a few thousand in large muscles that To as many as a few thousand in large muscles that perform less complex activities such as the perform less complex activities such as the quadriceps quadriceps

Manual of Structural KinesiologyNeuromuscular Fundamentals

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Muscle Length - Muscle Length - Tension RelationshipTension Relationship

Generally, depending upon muscle involvedGenerally, depending upon muscle involved Greatest amount of tension can be developed when a Greatest amount of tension can be developed when a

muscle is stretched between 100% to 130% of its muscle is stretched between 100% to 130% of its resting lengthresting length Stretch beyond 100% to 130% of resting length Stretch beyond 100% to 130% of resting length

significantly decreases the amount of force production significantly decreases the amount of force production

A proportional decrease in ability to develop tension A proportional decrease in ability to develop tension occurs as a muscle is shortenedoccurs as a muscle is shortened When shortened to around 50% to 60% of resting When shortened to around 50% to 60% of resting

length ability to develop contractile tension is length ability to develop contractile tension is essentially reduced to zeroessentially reduced to zero

Muscle Length - Muscle Length - Tension RelationshipTension Relationship

Maximal ability of a muscle Maximal ability of a muscle to develop tension & exert to develop tension & exert force varies depending upon force varies depending upon the length of the muscle the length of the muscle during contractionduring contraction


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Muscle Length - Tension Muscle Length - Tension RelationshipRelationship

Ex. 1 Increasing ability to Ex. 1 Increasing ability to exert forceexert force squat slightly to stretch the squat slightly to stretch the

gastroc, hamstrings, & gastroc, hamstrings, & quadriceps before quadriceps before contracting same muscles contracting same muscles concentrically to jumpconcentrically to jump

Ex. 2. Reducing ability to Ex. 2. Reducing ability to exert forceexert force isolate the gluteus maximus isolate the gluteus maximus

by maximally shortening the by maximally shortening the hamstrings with knee flexionhamstrings with knee flexion


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Reciprocal Inhibition Reciprocal Inhibition or Innervationor Innervation

Antagonist muscles groups must relax & lengthen Antagonist muscles groups must relax & lengthen when the agonist muscle group contractswhen the agonist muscle group contracts This reciprocal innervation effect occurs through This reciprocal innervation effect occurs through

reciprocal inhibition of the antagonistsreciprocal inhibition of the antagonists Activation of the motor units of the agonists causes a Activation of the motor units of the agonists causes a

reciprocal neural inhibition of the motor units of the reciprocal neural inhibition of the motor units of the antagonistsantagonists

This reduction in neural activity of the antagonists allows This reduction in neural activity of the antagonists allows them to subsequently lengthen under less tensionthem to subsequently lengthen under less tension Biceps contracts triceps must relaxBiceps contracts triceps must relax

Active & Passive Active & Passive InsufficiencyInsufficiency

As muscle shortens its ability to exert force As muscle shortens its ability to exert force diminishesdiminishes Active insufficiencyActive insufficiency is reached when the muscle is reached when the muscle

becomes shortened to the point that it can not becomes shortened to the point that it can not generate or maintain active tensiongenerate or maintain active tension

Passively insufficiencyPassively insufficiency is reached when the opposing is reached when the opposing muscle becomes stretched to the point where it can muscle becomes stretched to the point where it can no longer lengthen & allow movementno longer lengthen & allow movement

Active InsufficiencyActive Insufficiency When a multi-joint muscle contracts When a multi-joint muscle contracts

simultaneously over 2 joints the muscle is simultaneously over 2 joints the muscle is unable to generate a maximum muscle unable to generate a maximum muscle contraction.contraction. Ex. Rectus femorus contracts concentrically to Ex. Rectus femorus contracts concentrically to

both flex the hip & extend the kneeboth flex the hip & extend the knee Hamstrings: contracts both knee flexion and hip Hamstrings: contracts both knee flexion and hip

extensionextension

Gastrocnemius: Knee flexion and plantar Gastrocnemius: Knee flexion and plantar flexionflexion

Biceps brachii: shoulder flexion and elbow flexionBiceps brachii: shoulder flexion and elbow flexion

Manual of Structural Kinesiology

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Passive InsufficiencyPassive Insufficiency Agonist muscle unable to reach full Agonist muscle unable to reach full

range of motion because of range of motion because of inadequate length of antagonistic two inadequate length of antagonistic two joint muscle.joint muscle.

Hamstrings can’t stretch enough to Hamstrings can’t stretch enough to allow both maximal hip flexion & allow both maximal hip flexion & maximal knee extension.maximal knee extension.

Knee flexion cannot be fully achieved Knee flexion cannot be fully achieved if the hip is fully extended. Rectus if the hip is fully extended. Rectus femoris length limits motion.femoris length limits motion.

Finger flexion is limited if wrist flexion Finger flexion is limited if wrist flexion occurs simultaneously. occurs simultaneously.

ProprioceptionProprioception

Subconscious mechanism by which body is able to Subconscious mechanism by which body is able to regulate posture & movement by responding to stimuli regulate posture & movement by responding to stimuli originating in proprioceptors of the joints, tendons, originating in proprioceptors of the joints, tendons, muscles, & inner earmuscles, & inner ear

Proprioceptors - internal receptors located in skin, Proprioceptors - internal receptors located in skin, joints, muscles, & tendons which provide feedback joints, muscles, & tendons which provide feedback relative to:relative to:

tension, length, & contraction state of muscle.tension, length, & contraction state of muscle. position of body & limbs.position of body & limbs. movements of joints.movements of joints.


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Proprioception Proprioception Proprioceptors specific to musclesProprioceptors specific to muscles

Muscles spindlesMuscles spindles concentrated primarily in muscle belly between the fibersconcentrated primarily in muscle belly between the fibers

sensitive to stretch & rate of stretchsensitive to stretch & rate of stretch

Insert into connective tissue within muscle & run parallel with Insert into connective tissue within muscle & run parallel with muscle fibersmuscle fibers

Golgi tendon organs (GTO)Golgi tendon organs (GTO) found serially in the tendon close to muscle tendon junctionfound serially in the tendon close to muscle tendon junction sensitive to both muscle tension & active contractionsensitive to both muscle tension & active contraction much less sensitive to stretch than muscle spindlesmuch less sensitive to stretch than muscle spindles require a greater stretch to be activatedrequire a greater stretch to be activated

Muscle spindleMuscle spindle

Muscle spindles & Muscle spindles & myotatic or stretch reflexmyotatic or stretch reflex

1.1. Rapid muscle stretch occursRapid muscle stretch occurs

2.2. Afferent Impulse is sent to Afferent Impulse is sent to the CNSthe CNS

3.3. CNS activates motor CNS activates motor neurons of agonist muscle neurons of agonist muscle while inhibiting the while inhibiting the antagonist muscle. antagonist muscle.

4.4. Stretched or agonistic Stretched or agonistic muscle contractsmuscle contracts

Monosynaptic ReflexMonosynaptic Reflex Ex. Knee jerk or patella tendon reflexEx. Knee jerk or patella tendon reflex


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Golgi Tendon OrganGolgi Tendon Organ Golgi tendon organGolgi tendon organ

Tension in tendons & GTO increases Tension in tendons & GTO increases as muscle contract, which activates as muscle contract, which activates GTOGTO

1.1. GTO stretch threshold is reachedGTO stretch threshold is reached

2.2. Impulse is sent to CNS Impulse is sent to CNS

3.3. CNS causes muscle to relaxCNS causes muscle to relax

4.4. facilitates activation of antagonists as facilitates activation of antagonists as a protective mechanisma protective mechanism

GTO protects us from an excessive GTO protects us from an excessive contraction by causing its muscle to contraction by causing its muscle to relaxrelax


Chapter 3Chapter 3Basic Biomechanical Basic Biomechanical Factors & ConceptsFactors & Concepts


Basic Biomechanical Factors & Concepts

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BiomechanicsBiomechanics BiomechanicsBiomechanics - study of the mechanics as it relates to the - study of the mechanics as it relates to the

functional and anatomical analysis of biological systems functional and anatomical analysis of biological systems Necessary to study the bodyNecessary to study the body’’s mechanical s mechanical

characteristics & principles to understand its characteristics & principles to understand its movementsmovements

MechanicsMechanics - study of physical actions of forces - study of physical actions of forces

Musculoskeletal system may be thought of as a series of simple Musculoskeletal system may be thought of as a series of simple machinesmachines Machines - used to increase mechanical advantageMachines - used to increase mechanical advantage Consider mechanical aspect of each component in analysis with Consider mechanical aspect of each component in analysis with

respect to componentsrespect to components’’ machine-like function machine-like function

LeversLevers

Humans moves through a system of leversHumans moves through a system of levers

Levers cannot be changed, but they can be utilized more Levers cannot be changed, but they can be utilized more efficientlyefficiently lever - a rigid bar that turns about an lever - a rigid bar that turns about an axisaxis of rotation or a of rotation or a

fulcrumfulcrum axis - point of rotation about which lever movesaxis - point of rotation about which lever moves

Levers rotate about an axis as a result of Levers rotate about an axis as a result of forceforce (effort, (effort, E)E) being being applied to cause its movement against a applied to cause its movement against a resistanceresistance or weight or weight

In the bodyIn the body bones represent the barsbones represent the bars joints are the axesjoints are the axes muscles contract to apply forcemuscles contract to apply force


LeversLevers

Three points determine type of lever & for which Three points determine type of lever & for which kind of motion it is best suitedkind of motion it is best suited Axis Axis (A)(A)- fulcrum - the point of rotation - fulcrum - the point of rotation

Point Point (F)(F) of force application (usually muscle of force application (usually muscle insertion) - effortinsertion) - effort

Point Point (R)(R) of resistance application (center of of resistance application (center of gravity of lever) or (location of an external gravity of lever) or (location of an external resistance)resistance)



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Levers SystemsLevers Systems

11stst class lever – axis class lever – axis (A)(A) somewhere somewhere between force between force (F)(F) & resistance & resistance (R)(R)

22ndnd class lever – resistance class lever – resistance (R)(R) somewhere somewhere between axis between axis (A)(A) & force & force (F)(F)

33rdrd class lever – force class lever – force (F)(F) somewhere somewhere between axis between axis (A)(A) & resistance & resistance (R)(R)


LeversLevers



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• AFRAFR3rd3rd

| | Resistance Arm Resistance Arm ||

• ARFARF2nd2nd

| | Force Arm Force Arm ||

• FARFAR1st1st

AA

FF RR

| Force ArmForce Arm || | Resistance Arm Resistance Arm ||

AA

RR

| | Resistance Arm Resistance Arm ||

FF

AA

RR

| | Force Arm Force Arm ||

FF

First-class LeversFirst-class Levers

Produce balanced movements Produce balanced movements when axis is midway between when axis is midway between force & resistance (e.g., seesaw force & resistance (e.g., seesaw or scissors)or scissors)

Produce speed & range of Produce speed & range of motion when axis is close to motion when axis is close to force, (triceps in elbow force, (triceps in elbow extension)extension)

Produce force motion when axis Produce force motion when axis is close to resistance (crowbar)is close to resistance (crowbar)


First-class LeversFirst-class Levers Head balanced on neck in flexing/extendingHead balanced on neck in flexing/extending

Elbow extension in triceps applying force to Elbow extension in triceps applying force to olecranon olecranon (F)(F) in extending the non- in extending the non-supported forearm supported forearm (R)(R) at the elbow at the elbow (A)(A)

Agonist & antagonist muscle groups are Agonist & antagonist muscle groups are contracting simultaneously on either side of contracting simultaneously on either side of a joint axisa joint axis agonist produces force while antagonist agonist produces force while antagonist

supplies resistancesupplies resistance

First-class LeversFirst-class Levers

Force is applied where muscle inserts Force is applied where muscle inserts in bone, not in belly of musclein bone, not in belly of muscle Ex. in elbow extension with shoulder Ex. in elbow extension with shoulder

fully flexed & arm beside the ear, the fully flexed & arm beside the ear, the triceps applies force to the olecranon triceps applies force to the olecranon of ulna behind the axis of elbow jointof ulna behind the axis of elbow joint

As the applied force exceeds the As the applied force exceeds the amount of forearm resistance, the amount of forearm resistance, the elbow extendselbow extends


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LeversLevers

The mechanical advantage of levers may be The mechanical advantage of levers may be determined using the following equations:determined using the following equations:

Mechanical advantage =Mechanical advantage =

ResistanceResistanceForceForce

oror

Mechanical advantage =Mechanical advantage =

Length of force armLength of force armLength of resistance armLength of resistance arm

Torque and length of Torque and length of lever armslever arms

First class leversA, If the force arm & resistance arm are equal in length, a force equal to the resistance is required to balance it;B, As the force arm becomes longer, a decreasing amount of force is required to move a relatively larger resistance;C, As the force arm becomes shorter, an increasing amount of force is required to move a relatively smaller resistance

Second-class LeversSecond-class Levers

Produces force movements, Produces force movements, since a large resistance can be since a large resistance can be moved by a relatively small moved by a relatively small forceforce WheelbarrowWheelbarrow

NutcrackerNutcracker

Loosening a lug nutLoosening a lug nut

Raising the body up on the toesRaising the body up on the toes

Second-class LeversSecond-class Levers Plantar flexion of foot to raise the Plantar flexion of foot to raise the

body up on the toes where ball (A) body up on the toes where ball (A) of the foot serves as the axis as of the foot serves as the axis as ankle plantar flexors apply force to ankle plantar flexors apply force to the calcaneus (F) to lift the the calcaneus (F) to lift the resistance of the body at the tibial resistance of the body at the tibial articulation (R) with the footarticulation (R) with the foot

Relatively few 2Relatively few 2ndnd class levers in class levers in bodybody


Second class leversA, Placing the resistance halfway between the axis & the point of force application provides a MA of 2;B, Moving the resistance closer to the axis increases the MA, but decreases the distance that the resistance is moved;C, the closer the resistance is positioned to the point of force application the less of a MA, but the greater the distance it is moved

Third-class LeversThird-class Levers Produce speed & range-of-motion Produce speed & range-of-motion

movementsmovements

Most common in human bodyMost common in human body

Requires a great deal of force to move Requires a great deal of force to move even a small resistanceeven a small resistance Paddling a boatPaddling a boat

Shoveling - application of lifting force to a Shoveling - application of lifting force to a shovel handle with lower hand while upper shovel handle with lower hand while upper hand on shovel handle serves as axis of hand on shovel handle serves as axis of rotationrotation



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Third-class LeversThird-class Levers Biceps brachii in elbow flexionBiceps brachii in elbow flexion

Using the elbow joint (A) as the axis, Using the elbow joint (A) as the axis, the biceps brachii applies force at its the biceps brachii applies force at its insertion on radial tuberosity (F) to insertion on radial tuberosity (F) to rotate forearm up, with its center of rotate forearm up, with its center of gravity (R) serving as the point of gravity (R) serving as the point of resistance applicationresistance application


Third class leversA, a force greater than the resistance, regardless of the point of force application, is required due to the resistance arm always being longer;B, Moving the point of force application closer to the axis increases the range of motion & speed;C, Moving the point of force application closer to the resistance decreases the force needed


Long levers produce more Long levers produce more linear force and thus better linear force and thus better performance in some sports performance in some sports such as baseball, hockey, golf, such as baseball, hockey, golf, field hockey, etc.field hockey, etc.

For quickness, it is desirable For quickness, it is desirable to have a short lever armto have a short lever arm

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PulleysPulleys

Single pulleys function to Single pulleys function to change effective direction of change effective direction of force applicationforce application Mechanical advantage = 1Mechanical advantage = 1

Pulleys may be combined to Pulleys may be combined to form compound pulleys to form compound pulleys to increase mechanical advantageincrease mechanical advantage Each additional rope increases Each additional rope increases

mechanical advantage by 1mechanical advantage by 1

PulleysPulleys Ex. lateral malleolus acting as a pulley Ex. lateral malleolus acting as a pulley

around which tendon of peroneus longus around which tendon of peroneus longus runsruns As peroneus longus contracts, it pulls toward As peroneus longus contracts, it pulls toward

it belly (toward the knee)it belly (toward the knee) Using the lateral malleolus as a pulley, force Using the lateral malleolus as a pulley, force

is transmitted to plantar aspect of foot is transmitted to plantar aspect of foot resulting in eversion/plantarflexionresulting in eversion/plantarflexion

ForceForce

Muscles are the main source of force that produces or Muscles are the main source of force that produces or changes movement of a body segment, the entire changes movement of a body segment, the entire body, or some object thrown, struck, or stoppedbody, or some object thrown, struck, or stopped

Strong muscles are able to produce more force than Strong muscles are able to produce more force than weak musclesweak muscles both maximum and sustained exertion over a period of both maximum and sustained exertion over a period of

timetime



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ForceForce

ForcesForces either push or pull on an object in an attempt either push or pull on an object in an attempt to affect motion or shapeto affect motion or shape

Without forces acting on an object there would be no Without forces acting on an object there would be no motionmotion

Force - product of mass times accelerationForce - product of mass times acceleration

Mass - amount of matter in a bodyMass - amount of matter in a body



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ForceForce

The weight of a body segment or the entire body X the The weight of a body segment or the entire body X the speed of acceleration determines the forcespeed of acceleration determines the force Important in footballImportant in football Also important in activities using only a part of the bodyAlso important in activities using only a part of the body In throwing a ball, the force applied to the ball is equal In throwing a ball, the force applied to the ball is equal

to the weight of the arm times the speed of acceleration to the weight of the arm times the speed of acceleration of the armof the arm

Leverage factors are also importantLeverage factors are also important



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Mechanical loading Mechanical loading basicsbasics

Significant mechanical loads are generated & Significant mechanical loads are generated & absorbed by the tissues of the bodyabsorbed by the tissues of the body

Internal or external forces may cause these loadsInternal or external forces may cause these loads

Only muscles can actively generate internal force, but Only muscles can actively generate internal force, but tension in tendons, connective tissues, ligaments and tension in tendons, connective tissues, ligaments and joints capsules may generate passive internal forcesjoints capsules may generate passive internal forces



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Web SitesWeb SitesBiomechanics: The Magazine of Body Movement and Medicine

www.biomech.com/

Biomechanics World Widewww.uni-essen.de/~qpd800/WSITECOPY.html This site enables the reader to search the biomechanics

journals for recent information regarding mechanism of injury.

Kinesiology Biomechanics Classeswww.uoregon.edu/~karduna/biomechanics/kinesiology.htm A listing of numerous biomechanics and kinesiology class site

on the web with many downloadable presentations and notes

The Physics Classroomwww.physicsclassroom.com/ Numerous topics including the laws of motion and other physics

principles



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http://www.biomech.com/

http://www.uni-essen.de/~qpd800/WSITECOPY.html

http://www.uoregon.edu/~karduna/biomechanics/kinesiology.htm

http://www.physicsclassroom.com/

Web SitesWeb SitesEdquest

www.edquest.ca/pdf/sia84notes.pdf Text, pictures, and illustrations on simple and complex

machines

COSI Hands-on science centerswww.cosi.org/files/Flash/simpMach/sm1.swf A Flash site demonstrating simple machine explanations

EuclideanSpace - building a 3D worldwww.euclideanspace.com Information on how to simulate physical objects with

computer programs

Physics Homework Helphttp://tutor4physics.com/index.htm Physics formulas, principles, tutorials



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http://www.edquest.ca/pdf/sia84notes.pdf

http://www.cosi.org/files/Flash/simpMach/sm1.swf

http://www.euclideanspace.com/

http://tutor4physics.com/index.htm

Web SitesWeb SitesGRD Training Corporation

www.physchem.co.za Explanations of physics principles for in motion with quizzes

International Society of Biomechanics

www.isbweb.org/ Software, data, information, resources, yellow pages, conferences

Sports Coach—Levers

www.brianmac.demon.co.uk/levers.htm A basic review of levers with excellent links to the study of muscle

training & function.

Integrated Publishing

www.tpub.com/content/engine/14037/index.htm Engine mechanics



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http://www.physchem.co.za/

http://www.isbweb.org/

http://www.brianmac.demon.co.uk/levers.htm

Web SitesWeb SitesHuman Anatomy Online

http://innerbody.com/image/musfov.html An interactive site with details on the muscular and

nervous systems.

BBC Science & Naturehttp://bbc.co.uk/science/humanbody/body/interactives/3djigsaw_02/index.shtml An interactive site allowing you to select the innervation

for the muscles.

Functions of the Muscular System

http://training.seer.cancer.gov/anatomy/muscular Several pages with information on skeletal muscle

structure, types, and groups, along with unit review and quizzes.


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Web SitesWeb SitesU.S. National Library of Medicine’s Visible Human Project AnatQuest

Anatomic Images Online

http://anatline.nlm.nih.gov/AnatQuest/AwtCsViewer/aq-cutaway.html

A great resource using a cut-away viewer to see cadaver images throughout the body to identify the relevant anatomy.

The Physician and Sportsmedicine

www.physsportsmed.com/index.php?article=1476 www.physsportsmed.com/index.php?article=1476

Refining rehabilitation with proprioception training: expediting return to play.

Get Body Smart

www.getbodysmart.com/index.htm

An online interactive tutorial on the muscular and nervous systems.


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Web SitesWeb SitesNeurologic Exam: An anatomical approach

http://medlib.med.utah.edu/neurologicexam/home_exam.html A very thorough site on neurological exams, including numerous

movies with both normal and pathological results.

Cranial Nerves: Review infowww.gwc.maricopa.edu/class/bio201/cn/cranial.htm A good resource on the cranial nerves.

University of Arkansas for Medical Sciences Nerve tableshttp://anatomy.uams.edu/anatomyhtml/nerves.html Numerous tables of all nerves throughout the body.

Dermatomeswww.meddean.luc.edu/lumen/MedEd/GrossAnatomy/learnem/dermat/

main_der.htm An interactive review of the body’s dermatomes.


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Web SitesWeb SitesLoyola University Medical Education Network Master Muscle List

www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/dissector/mml

An interactive and graphical review of the muscles indexed alphabetically and by region.

Proprioception Exercises Can Improve Balance

http://sportsmedicine.about.com/library/weekly/aa062200.htm

Proprioception.

Muscular System

www.bio.psu.edu/faculty/strauss/anatomy/musc/muscular.htm

Cadavaric photos of the cat muscular system.

Functions of the Nervous System

http://training.seer.cancer.gov/anatomy/nervoushttp://training.seer.cancer.gov/anatomy/nervous

Several pages with information on the nervous system organization, nerve structure, unit review, and quizzes.


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Web SitesWeb Sites

Training for Proprioception & Function

www.coachr.org/proprio.htm

Information on improving body awareness movement efficiency.


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chapter 2 neuromuscular fundamentals

Documents

muscle lengthening

movement of body

joint movement orto

joint motion2

joint movementmuscles

joint angles

body segmentto slow

proximal attachment