Muscular SystemMuscular System

Functions of Muscular SystemFunctions of Muscular System

Stabilizes JointsStabilizes Joints

MovementMovement

Heat ProductionHeat Production

PosturePosture

Types of MuscleTypes of Muscle

SkeletalSkeletal– StriatedStriated– VoluntaryVoluntary– Connect by tendonsConnect by tendons

SmoothSmooth– NonstriatedNonstriated– InvoluntaryInvoluntary– double layered digestive trackdouble layered digestive track

CardiacCardiac– StriatedStriated– InvoluntaryInvoluntary– Wrap around heartWrap around heart

PosturePosture Good Posture Good Posture

– body alignment that favors function with least workbody alignment that favors function with least work– Standing PositionStanding Position

Head and chest held highHead and chest held high Chin, abdomen, buttocks pulled inChin, abdomen, buttocks pulled in Knees slightly bentKnees slightly bent Feet firmly on ground 6 in. apartFeet firmly on ground 6 in. apart

Poor Posture Poor Posture – puts abnormal strain on ligaments and bonesputs abnormal strain on ligaments and bones

MaintenanceMaintenance– Tonicity (muscle tone): muscles exert a pull against Tonicity (muscle tone): muscles exert a pull against

gravitygravity

TonicityTonicity

Continual, partial contraction of a Continual, partial contraction of a musclemuscle

FlaccidFlaccid– Muscles with less tone than normalMuscles with less tone than normal

SpasticSpastic– Muscles with more tone than normalMuscles with more tone than normal

Change in Muscle SizeChange in Muscle Size

Atrophy – decrease in muscle sizeAtrophy – decrease in muscle size– Bed Rest: lose 1% muscle strength/dayBed Rest: lose 1% muscle strength/day

Hypertrophy – increase in muscle Hypertrophy – increase in muscle sizesize

Muscles & AgeMuscles & Age

Infancy & ChildhoodInfancy & Childhood– Muscle coordination and control allows Muscle coordination and control allows

developmental sequences to occurdevelopmental sequences to occur AgingAging

– Muscles degenerate with ageMuscles degenerate with age

Characteristics of all MuscleCharacteristics of all Muscle ExcitabilityExcitability

– Respond to stimuliRespond to stimuli Contractility Contractility

– Actively shorten to exert a pullActively shorten to exert a pull– Tension that can be harnessed by CTTension that can be harnessed by CT

ExtensibilityExtensibility– Continue to contract over range of resting lengthsContinue to contract over range of resting lengths– Ex: smooth muscle can be stretched to several times its Ex: smooth muscle can be stretched to several times its

original length and still contract on stimulationoriginal length and still contract on stimulation ElasticityElasticity

– Return to original length after contractionReturn to original length after contraction

Types of Body MovementTypes of Body Movement

Origin-Origin-attachmentattachment to a immovable to a immovable bonebone

Insertion-Insertion- attachment to an movable attachment to an movable bonebone

Muscles are always attached to at Muscles are always attached to at least 2 pointsleast 2 points

Movement is attained due to a muscle Movement is attained due to a muscle moving an attached bonemoving an attached bone

Muscle AttachmentMuscle Attachment

Does NOT move when muscle contracts

Does move when

muscle contracts

Classification of Muscle Group Classification of Muscle Group ActionsActions

Agonist (Prime Mover)Agonist (Prime Mover)– Muscle most responsible for movementMuscle most responsible for movement

AntagonistAntagonist– Opposes prime moverOpposes prime mover– Provides precision and control during prime mover Provides precision and control during prime mover

contractioncontraction– Relaxes when prime mover contractsRelaxes when prime mover contracts

SynergistSynergist– Aid prime moverAid prime mover– Contract at same time as prime moverContract at same time as prime mover

FixatorFixator– Joint stabilizerJoint stabilizer– Maintains posture/balance during prime mover contractionMaintains posture/balance during prime mover contraction

FlexionFlexionTypes of Musculo-Skeletal Movemen

ExtensionExtension

HyperextensionHyperextension

Abduction, Adduction & Abduction, Adduction & CircumductionCircumduction

RotationRotation

More Types of More Types of Movement……Movement……

Inversion-Inversion- turn sole of foot medially turn sole of foot medially Eversion-Eversion- turn sole of foot laterally turn sole of foot laterally Pronation-Pronation- palm facing down palm facing down Supination-Supination- palm facing up palm facing up Opposition-Opposition- thumb touches tips of thumb touches tips of

fingers on the same handfingers on the same hand

The Skeletal The Skeletal MusclesMuscles

There are about 650 muscles There are about 650 muscles in the human body. They in the human body. They enable us to move, maintain enable us to move, maintain posture and generate heat. posture and generate heat. In this section we will only In this section we will only study a sample of the major study a sample of the major muscles. muscles.

Naming MusclesNaming Muscles

LocationLocation FunctionFunction ShapeShape Fiber directionFiber direction Number of heads/divisionsNumber of heads/divisions Points of attachmentPoints of attachment Muscle sizeMuscle size

FrontalisFrontalis Frontal boneFrontal bone

FemorisFemoris FemurFemur

GluteusGluteus Posterior of Posterior of hip/thighhip/thigh

OculiOculi EyeEye

OrisOris MouthMouth

RadialisRadialis RadiusRadius

UlnarisUlnaris UlnaUlna

BrachialisBrachialis ArmArm

Location FunctionAbductorAbductor Moves part away from Moves part away from

bodybody

AdductorAdductor Moves part toward bodyMoves part toward body

DepressoDepressorr

Lowers a partLowers a part

ExtensorExtensor Extends a partExtends a part

FlexorFlexor Flexes a partFlexes a part

LevatorLevator Elevates a partElevates a part

RotatorRotator Rotates a partRotates a part

ShapeDeltoidDeltoid Shaped like delta Shaped like delta

∆∆

OrbicularisOrbicularis CircularCircular

PlatyPlaty Flattened; Flattened; platelikeplatelike

QuadratusQuadratus SquareSquare

RhomboideuRhomboideuss

Diamond-shapedDiamond-shaped

TrapeziusTrapezius TrapezoidalTrapezoidal

Fiber Direction

ObliqueOblique Diagonal to midlineDiagonal to midline

RectusRectus Parallel to midlineParallel to midline

SphincterSphincter Circling an openingCircling an opening

TransversuTransversuss

Right angle to Right angle to midlinemidline

Muscle Fiber ArrangementMuscle Fiber Arrangement

ConvergentParallel Pennate Bipennate Sphincter

BicepBicep Two headsTwo heads

TricepTricep Three headsThree heads

QuadriceQuadricepp

Four headsFour heads

Number of divisions

SizeBrevisBrevis ShortShort

LongusLongus LongLong

MagnusMagnus LargeLarge

MaximusMaximus LargestLargest

MediusMedius Moderately sizedModerately sized

MinimusMinimus SmallerSmaller

Raises eyebrows

Frowning

Blinking

Laughing

Puckering

Whistling, smiling

Mastication

Mastication

Flexes head

Moves head

Moves head

Flexes head

Superficial Back MusclesSuperficial Back Muscles•Large, fan-shaped muscles provide force in a wide range of body positions

-EX: leaning back to straight vertical and all points in between.

Pull the arm down,Stabilize torso during many movements (EX: bench press)

Shrugging, pulling scapulas together and down

Stabilize shoulder joint, pull arm back

Rotator cuffmuscles

Shoulder movement

Trunk Muscles - ThoraxTrunk Muscles - Thorax

Elevate ribs

Trunk MusclesTrunk MusclesAbdomenAbdomen

Flexes trunk

Compresses abdomen

StabilizesLower back

Upper ArmUpper Arm

Extends forearm

Flexes Upper arm

FlexorsFlexors

ExtensorsExtensors

Upper LegUpper Leg

Quadricep Femoris

Deep muscleVastus intermedius

Semimembranosus

Semitendinosus

Biceps femoris

Lower LegLower Leg

Plantar flexion

FootFoot

Anal and Urogenital MusclesAnal and Urogenital Muscles

LLeevveer r

SSyysstteemmss

P = Force (push or pull) Contracting MuscleF = Fulcrum JointL = Load Weights, etc

1st Class2nd Class

3rd Class

-mysium=CT membrane

and tendon sheath

Muscle fiber membrane

Sarcoplasm

Muscle cell (fiber)cytoplasm

Network of tubules and sacs: pumps calcium ions in from sarcoplasm to store in sacs

Bundle of microfilaments; almost fill sarcoplasm

Basic contractile unit of muscle fiber

Z line Z line

H zone

A bandI band

Length of myosin heads (wide, dark stripes)

Length of actin (thin, light stripes)

Space betweenactin

Allows impulses to travel along sarcolemma deeper into muscle cell (fiber) Allows impulse traveling

down T tubule to stimulate adjacent sacs

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__sarcomere_contraction.html

MyofilamentsMyofilamentsHolds tropomyosin in place Covers active site on actin

Attracted to actin and forms crossbridge

protein molecules

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__breakdown_of_atp_and_cross-bridge_movement_during_muscle_contraction.html

ContractionContraction

1. Synaptic vesicle travels down motor neuron and binds to motor endplate2. Acetylcholine released into synaptic cleft3. Ach binds to receptor on sarcolemma4. Impulse travels along sarcolemma and down t-tubules5. Calcium released from sarcoplasmic reticulum6. Calcium binds to troponin causing conformation change7. tropomyosin shifts to expose active site on actin8. myosin heads bind to actin9. actin filaments are pulled past the myosin head; head unattaches and reattaches to a

new site….repeat

Sliding Filament Theory - sliding of thin filaments toward center of each sarcomere shortens the myofibril and muscle fiber.

troponintropomyosin

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__action_potentials_and_muscle_contraction.html

Excitation & ContractionExcitation & Contraction

(neurotransmitter)

Motor endplateSynaptic cleft

Synaptic vesicle

Impulse sent to muscle fiber Muscle fiber creates movement

Neuromuscular junction

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__function_of_the_neuromuscular_junction__quiz_1_.html

Motor UnitMotor Unit

Smaller # fibers – more precise movement

Larger # fibers – more powerful contraction

•Quick jerk due to brief threshold stimulus•One twitch – 1/10 sec•Rarely occur

•Gradual, step-like increase in contraction strength•Series of twitch contractions 1 sec apart•Muscle contracts more forcefully after it has contracted a few times, then when it first contracts•Warm-up before exercise

•Smooth, sustained contractions•Coordinated contractions of different motor units•Multiple twitch waves add together to sustain muscle tension for longer time

•Very short periods of relaxation between peaks of tension

•Twitch waves fused into a single, sustained peak

All or NONE SR releasing Ca+2

Ca+2 bind to troponin; Cross-bridging

Length-tension RelationshipLength-tension Relationship

Sarcomere compressed

Muscle can’t develop tension

Optimal length

Strongest maxcontraction possible

Overstretched

Muscle can’t develop tension due to filamentstoo far apart

Energy SourcesEnergy Sources ATPATP

– Hydrolysis into ADP yields energy required for contractionHydrolysis into ADP yields energy required for contraction– ATP binds to myosin head in order to pull actinATP binds to myosin head in order to pull actin– Fibers continually resynthesize ATP from breaking down Fibers continually resynthesize ATP from breaking down

creatine phosphate (requires glucose and oxygen)creatine phosphate (requires glucose and oxygen) Glucose & oxygenGlucose & oxygen

– Hemoglobin transfers OHemoglobin transfers O22 to muscle fiber to muscle fiber

– Fiber stores glucose as glycogenFiber stores glucose as glycogen

– At rest: Excess OAt rest: Excess O22 in sarcoplasm is bound to myoglobin in sarcoplasm is bound to myoglobin temporarilytemporarily

– Exercise: OExercise: O22 concen. Decreases in muscle, so myoglobin concen. Decreases in muscle, so myoglobin resupplies muscle with Oresupplies muscle with O22

RespirationRespiration Aerobic RespirationAerobic Respiration

– Requires ORequires O22

– Produces max amount of energy available from Produces max amount of energy available from each glucose moleculeeach glucose molecule

Anaerobic RespirationAnaerobic Respiration– Occurs when lack of OOccurs when lack of O22 – Forms lactic acidForms lactic acid

During exerciseDuring exercise Muscles “burn”Muscles “burn”

– OO22 debt debt Heavy breathing during exercise in order to process Heavy breathing during exercise in order to process

lactic acidlactic acid

Muscle FatigueMuscle Fatigue

Muscles loses ability to contract due Muscles loses ability to contract due to lack of ATPto lack of ATP

Lactic acid build upLactic acid build up Cramp – muscle contracts Cramp – muscle contracts

spasmodically, but does not relax spasmodically, but does not relax completelycompletely

Most body movements are a result of both types

MyopathiesMyopathies MyalgiaMyalgia - muscle pain due to overstretching/tearing of muscle fibers - muscle pain due to overstretching/tearing of muscle fibers FibromyalgiaFibromyalgia – widespread muscle and CT pain – widespread muscle and CT pain Strain Strain – caused by overexertion/trauma and can lead to muscle tear– caused by overexertion/trauma and can lead to muscle tear MyositisMyositis - any muscle inflammation - any muscle inflammation FibromyositisFibromyositis - tendon inflammation along with myositis - tendon inflammation along with myositis CrampsCramps

– Painful muscle spasms Painful muscle spasms – Due to mild myositis, fibromyositis, irritation, iron, and water imbalanceDue to mild myositis, fibromyositis, irritation, iron, and water imbalance– Charley HorseCharley Horse

Intense muscle spasmsIntense muscle spasms Last few seconds to few hoursLast few seconds to few hours Caused by injury or overuseCaused by injury or overuse

– DehydrationDehydration– Low K+ or Ca+2Low K+ or Ca+2– Nerve irritated Nerve irritated

TreatmentTreatment– Stop activityStop activity– Stretch and massageStretch and massage– Heat to relax muscleHeat to relax muscle– Ice when spasm is overIce when spasm is over

MyopathiesMyopathies ContusionContusion

– Muscle bruise, local internal bleeding and inflammationMuscle bruise, local internal bleeding and inflammation– Crush injury: severe trauma to muscle, releasing fibers into Crush injury: severe trauma to muscle, releasing fibers into

bloodstream (life threatening)bloodstream (life threatening) Poliomyelitis (Poilio)Poliomyelitis (Poilio)

– Viral infection of nerves controlling skeletal movementViral infection of nerves controlling skeletal movement– Causes partial or full paralysis and deathCauses partial or full paralysis and death– Vaccine created in US in 1950s, but not everywhereVaccine created in US in 1950s, but not everywhere

Muscular DystrophyMuscular Dystrophy– Genetic disease caused by muscle atrophyGenetic disease caused by muscle atrophy– Some forms are fatalSome forms are fatal– Most common form is Duchenne Muscular Dystrophy (DMD)Most common form is Duchenne Muscular Dystrophy (DMD)

Myasthenia GravisMyasthenia Gravis– Autoimmune disease that attacks muscle cells at NM junctionAutoimmune disease that attacks muscle cells at NM junction– Muscle weaknessMuscle weakness– Can become a crisis and affect all four limbsCan become a crisis and affect all four limbs– Could die of respiratory failureCould die of respiratory failure

MyopathiesMyopathies HerniasHernias

– ““protrusion”protrusion”– Reducible – can manipulate protruding organ back into abdominal Reducible – can manipulate protruding organ back into abdominal

cavitycavity– Strangulated – blood flow to organ is stopped; obstruction, Strangulated – blood flow to organ is stopped; obstruction,

gangrene, pain. Vomiting, emergency surgerygangrene, pain. Vomiting, emergency surgery– TypesTypes

Inguinal – hernia extends into inguinal canal into scrotum or Inguinal – hernia extends into inguinal canal into scrotum or labia; affects more maleslabia; affects more males

Femoral – affects more women below groin area due to Femoral – affects more women below groin area due to pregnancypregnancy