the muscular system -...

66The Muscular SystemThe Muscular System

Yong Jeong, MD, PhDg g

Department of Bio and Brain Engineering

The Muscular System

•Muscles are responsible for all types of body movement

•Three basic muscle types are found in theThree basic muscle types are found in the body

Sk l t l l•Skeletal muscle•Cardiac muscle•Smooth muscle


Characteristics of Muscles

•Skeletal and smooth muscle cells are elongated (muscle cell = muscle fiber)

•Contraction and shortening of muscles is dueContraction and shortening of muscles is due to the movement of microfilamentsAll l h t i l•All muscles share some terminology•Prefixes myo and mys refer to “muscle”y y•Prefix sarco refers to “flesh”


Comparison of Skeletal, Cardiac, and Smooth Muscles

Ch t i ti Sk l t l C di S thCharacteristic Skeletal Cardiac Smooth

Body location Attached to bone or skin (for some

Walls of the heart Mostly in walls of visceral organsor skin (for some

facial muscles)visceral organs (other than the heart)

Cell shape and appearance

Single, very long, cylindrical, multinucleate

Branching chains of cells, uninucleate,

Single, fusiform, uninucleate, no striations

cells with very obvious striations

striations, intercalated discs

Connective Endomysium Endomysium EndomysiumConnective tissue components

Endomysium, perimysium, and epimysium

Endomysium Endomysium


Comparison of Skeletal, Cardiac, and Smooth Muscles

Ch t i ti Sk l t l C di S thCharacteristic Skeletal Cardiac Smooth

Regulation of contraction

Voluntary Involuntary Involuntarycontraction

Speed of contraction

Slow to fast Slow Very slow

Rhythmic No Yes Yes in someRhythmic contractions

No Yes Yes, in some


Skeletal Muscle Characteristics

•Most are attached by tendons to bones•Cells are multinucleateStriated have visible banding•Striated—have visible banding

•Voluntary—subject to conscious control


Connective Tissue Wrappings of Skeletal Muscle

•Cells are surrounded and bundled by connective tissue•Endomysium—encloses a single muscle fiberfiber

•Perimysium—wraps around a fascicle (bundle) of muscle fibers

•Epimysium—covers the entire skeletalEpimysium covers the entire skeletal muscleFascia on the outside of the epimysium


•Fascia—on the outside of the epimysium

Musclefiber

Blood vessel

Perimysium

(cell)

Epimysium(wraps entire( pmuscle)

Fascicle(wrapped by(wrapped byperimysium)

Endomysium(betweenfibers)

T dTendon

Bone

© 2012 Pearson Education, Inc. Figure 6.1

Skeletal Muscle Attachments

•Epimysium blends into a connective tissue attachment•Tendons—cord-like structuresTendons cord like structures

•Mostly collagen fibers•Often cross a joint due to toughness and small size

•Aponeuroses—sheet-like structuresAtt h l i di tl t b•Attach muscles indirectly to bones, cartilages, or connective tissue coverings


Skeletal Muscle Attachments

•Sites of muscle attachment•BonesCartilages•Cartilages

•Connective tissue coverings


Smooth Muscle Characteristics

•Lacks striations•Spindle-shaped cellsSingle nucleus•Single nucleus

•Involuntary—no conscious control•Found mainly in the walls of hollow organs


Circular layerof smooth muscle(longitudinal viewof cells)Mucosa

Longitudinal layerLongitudinal layerof smooth muscle(cross-sectionali f ll )

Submucosa

© 2012 Pearson Education, Inc. Figure 6.2a

view of cells)(a)

Cardiac Muscle Characteristics

•Striations•Usually has a single nucleusBranching cells•Branching cells

•Joined to another muscle cell at an intercalated disc

•InvoluntaryInvoluntary•Found only in the walls of the heart


Cardiacmusclemusclebundles

© 2012 Pearson Education, Inc. Figure 6.2b(b)

Skeletal Muscle Functions

•Produce movement•Maintain postureStabilize joints•Stabilize joints

•Generate heat


Microscopic Anatomy of Skeletal Muscle

•Sarcolemma—specialized plasma membrane•Myofibrils—long organelles inside muscle cellSarcoplasmic reticulum specialized smooth•Sarcoplasmic reticulum—specialized smooth endoplasmic reticulum


Cytoplasmic Organelles

•Cytoskeleton•Three different types of elements•Microfilaments I t di t•Intermediate filaments

•Microtubules


Figure 3.7b–d

Sarcolemma

Myofibril

Dark(A) band

Light(I) band

Nucleus

(a) Segment of a muscle fiber (cell)



•Myofibrils are aligned to give distinct bands•I band = light band

Contains only thin filaments•Contains only thin filaments•A band = dark band

•Contains the entire length of the thick filamentsfilaments


Z disc H zone Z disc

Thin (actin) filamentThick (myosin) filament

(b) Myofibril or fibril(complex organelle

I band A band I band M line(complex organellecomposed of bundlesof myofilaments)

© 2012 Pearson Education, Inc. Figure 6.3b


•Sarcomere—contractile unit of a muscle fiber•Organization of the sarcomere

Myofilaments•Myofilaments•Thick filaments = myosin filaments•Thin filaments = actin filaments



•Thick filaments = myosin filaments•Composed of the protein myosin•Has ATPase enzymesHas ATPase enzymes•Myosin filaments have heads (extensions, or cross bridges)cross bridges)

•Myosin and actin overlap somewhat•Thin filaments = actin filaments

•Composed of the protein actinp p•Anchored to the Z disc


Z di

Sarcomere

M lineZ diZ disc Z disc

Thin (actin) filament

Thick (myosin) filament

(c) Sarcomere (segment of a myofibril)

© 2012 Pearson Education, Inc. Figure 6.3c


•At rest, within the A band there is a zone that lacks actin filaments •Called either the H zone or bare zoneCalled either the H zone or bare zone

•Sarcoplasmic reticulum (SR) •Stores and releases calcium•Surrounds the myofibrilSurrounds the myofibril


Thick filament Bare zone Thin filament

(d) Myofilament structure (within one sarcomere)

© 2012 Pearson Education, Inc. Figure 6.3d

Stimulation and Contraction of Single Skeletal Muscle Cells

•Excitability (also called responsiveness or irritability)—ability to receive and respond to a y) y pstimulus

•Contractility ability to shorten when an•Contractility—ability to shorten when an adequate stimulus is received

•Extensibility—ability of muscle cells to be stretched

•Elasticity—ability to recoil and resume resting length after stretching


length after stretching

The Nerve Stimulus and Action Potential

•Skeletal muscles must be stimulated by a motor neuron (nerve cell) to contract

•Motor unit—one motor neuron and all theMotor unit one motor neuron and all the skeletal muscle cells stimulated by that neuron


Spinal cordAxon terminals at neuromuscular junctions

Motor unit 1

Motor unit 2unit 1 unit 2

Nerve

Axon ofmotorMotor neuron

cell bodies neuroncell bodies

Muscle Muscle fibers

© 2012 Pearson Education, Inc. Figure 6.4a(a)

Axon terminals at neuromuscular junctions Muscle fibers

Branching axonto motor unit


(b)


•Neuromuscular junction•Association site of axon terminal of the motor neuron and musclemotor neuron and muscle

PLAY A&P Flix™: Events at the Neuromuscular Junction



•Synaptic cleft •Gap between nerve and muscleNerve and muscle do not make contact•Nerve and muscle do not make contact

•Area between nerve and muscle is filled with interstitial fluid

•Action potential reaches the axon terminal ofAction potential reaches the axon terminal of the motor neuronC l i h l d l i i t•Calcium channels open and calcium ions enter the axon terminal


Transmission of Nerve Impulse to Muscle

•Calcium ion entry causes some synaptic vesicles to release their contents (acetylcholine, a neurotransmitter) by ( y , ) yexocytosis

•Neurotransmitter chemical released by nerve•Neurotransmitter—chemical released by nerve upon arrival of nerve impulse in the axon terminalterminal•The neurotransmitter for skeletal muscle is acetylcholine (ACh)


Transmission of Nerve Impulse to Muscle

•Acetylcholine attaches to receptors on the sarcolemma of the muscle cell

•In response to the binding of ACh to aIn response to the binding of ACh to a receptor, the sarcolemma becomes permeable to sodium (Na+)to sodium (Na )

•Sodium rushes into the cell generating an action potential and potassium leaves the cell

•Once started, muscle contraction cannot beOnce started, muscle contraction cannot be stopped


S naptic esicle containing AChSynaptic vesicle containing ACh

Axon terminal of motor neuronMitochondrion

Action potential reaches axonterminal of motor neuron.1

Ca2+

Synapticcleft

Sarcolemma

Fusing synaptic

Ca2+

Fusing synapticvesicleSarcoplasmof muscle fiberFolds of

lACh

ACh

sarcolemmareceptor

© 2012 Pearson Education, Inc. Figure 6.5, step 1




Ca2+

Fusing synaptic

Ca2+

SarcolemmaSynapticcleft

Calcium (Ca2+) channelsopen and Ca2+ enters the axon terminal.

2


lACh

ACh

sarcolemmareceptor





Ca2+

Fusing synaptic

Ca2+



2


lACh

AChCa2+ entry causes somesynaptic vesicles to release theircontents (acetylcholine a

3

sarcolemmareceptorcontents (acetylcholine, a neurotransmitter) by exocytosis.


S naptic esicle containing AChAction potential reaches axon

terminal of motor neuron.

Synaptic vesicle containing ACh


1


Ca2+

Fusing synaptic

Ca2+2


Ca2+ entry causes somesynaptic vesicles to release theircontents (acetylcholine a


lACh

ACh3

contents (acetylcholine, a neurotransmitter) by exocytosis.

Acetylcholine diffuses acrossthe synaptic cleft and binds toreceptors in the sarcolemma.

sarcolemmareceptor

4

p


ACh binds and channels openthat allow simultaneous passageof Na+ into the muscle fiber and K+ out of the muscle fiber. More

5Ion channel insarcolemma opens;ions pass.

Na+ K+

Na+ ions enter than K+ ions leaveand this produces a local changein the electrical conditions of themembrane (depolarization), whicheventually leads to an actioneventually leads to an actionpotential.


ACh effects are ended by its6

Ion channel closed;ions cannot pass.Na+

Degraded AChACh

ACh effects are ended by itsbreakdown in the synaptic cleft bythe enzyme acetylcholinesterase.

6

AcetylcholinesteraseK+


S ll t i

Neuromuscular junction

NerveMuscle cellor fiber

Small twig

Match

Nervefiber Striations

Matchflame

Flame ignites the twig.

Flame spreads rapidly along the twig.

Na+ diffusesinto the cell. Action potential spreads

rapidly along the sarcolemma.1 2

12

(b)(a)

© 2012 Pearson Education, Inc. Figure 6.6a-b

The Sliding Filament Theory of Muscle Contraction

A i i b i h d•Activation by nerve causes myosin heads (cross bridges) to attach to binding sites on the thin filament

•Myosin heads then bind to the next site of theMyosin heads then bind to the next site of the thin filament and pull them toward the center of the sarcomereof the sarcomere

•This continued action causes a sliding of the i l h imyosin along the actin

•The result is that the muscle is shortened


(contracted)

Myosin Actin

Z ZZ HI

ZA I

(a)(a)

Z Z

© 2012 Pearson Education, Inc. Figure 6.7a–b(b)

ZI A I

Z

Protein complex In a relaxed muscle cell, the regulatory proteins formingp In a relaxed muscle cell, the regulatory proteins formingpart of the actin myofilaments prevent myosin binding(see a). When an action potential (AP) sweeps along itssarcolemma and a muscle cell is excited, calcium ions(Ca2+) are released from intracellular storage areas (the

f th l i ti l )

Myosinmyofilament

Actinmyofilament(a)

sacs of the sarcoplasmic reticulum).


Myosin-binding site C 2 The flood of calcium acts as the final trigger forMyosin binding site Ca2+ The flood of calcium acts as the final trigger forcontraction, because as calcium binds to the regulatoryproteins on the actin filaments, the proteins undergo a change in both their shape and their position on the thinfilaments. This action exposes myosin-binding sites on

Upper part of thick filament only(b)

y gthe actin, to which the myosin heads can attach (see b),and the myosin heads immediately begin seeking out binding sites.


PLAY A&P Flix™: The Cross Bridge Cycle


Contraction of Skeletal Muscle

•Muscle fiber contraction is “all or none”•Within a skeletal muscle, not all fibers may be stimulated during the same intervalstimulated during the same interval

•Different combinations of muscle fiber t ti i diff icontractions may give differing responses

•Graded responses—different degrees of p gskeletal muscle shortening


Contraction of Skeletal Muscle

•Graded responses can be produced by changing:•The frequency of muscle stimulationThe frequency of muscle stimulation•The number of muscle cells being stimulated

t tiat one time


Types of Graded Responses

•Twitch•Single, brief contractionNot a normal muscle function•Not a normal muscle function



•Summing of contractions•One contraction is immediately followed by anotheranother

•The muscle does not completely return to a ti t t d t f tresting state due to more frequent

stimulations•The effects are added



•Unfused (incomplete) tetanus•Some relaxation occurs between contractions but nerve stimuli arrive at ancontractions but nerve stimuli arrive at an even faster rate than during summing of contractionscontractions

•Unless the muscle contraction is smooth and sustained, it is said to be in unfused tetanus



•Fused (complete) tetanus•No evidence of relaxation before the following contractionsfollowing contractions

•Frequency of stimulations does not allow for l ti b t t tirelaxation between contractions

•The result is a smooth and sustained muscle contraction


Muscle Response to Strong Stimuli

•Muscle force depends upon the number of fibers stimulated

•More fibers contracting results in greaterMore fibers contracting results in greater muscle tensionM l ti t t t l th•Muscles can continue to contract unless they run out of energy


Energy for Muscle Contraction

•Initially, muscles use stored ATP for energy•ATP bonds are broken to release energyOnly 4 6 seconds worth of ATP is stored by•Only 4–6 seconds worth of ATP is stored by muscles

•After this initial time, other pathways must be utilized to produce ATPp



•Direct phosphorylation of ADP by creatine phosphate (CP)•Muscle cells store CPMuscle cells store CP

•CP is a high-energy molecule•After ATP is depleted, ADP is left•CP transfers a phosphate group to ADP toCP transfers a phosphate group to ADP, to regenerate ATPCP li h t d i l th 15•CP supplies are exhausted in less than 15 seconds


•About 1 ATP is created per CP molecule


•Aerobic respiration•Glucose is broken down to carbon dioxide and water releasing energy (about 32 ATP)and water, releasing energy (about 32 ATP)

•A series of metabolic pathways occur in the it h d imitochondria

•This is a slower reaction that requires qcontinuous oxygen

•Carbon dioxide and water are produced•Carbon dioxide and water are produced



•Anaerobic glycolysis and lactic acid formation•Reaction that breaks down glucose withoutoxygenoxygen

•Glucose is broken down to pyruvic acid to d b t 2 ATPproduce about 2 ATP

•Pyruvic acid is converted to lactic acidy•This reaction is not as efficient, but is fast

H t f l d d•Huge amounts of glucose are needed•Lactic acid produces muscle fatigue


p g

Muscle Fatigue and Oxygen Deficit

•When a muscle is fatigued, it is unable to contract even with a stimulus

•Common cause for muscle fatigue is oxygenCommon cause for muscle fatigue is oxygen debt

O t b “ id” t ti t•Oxygen must be “repaid” to tissue to remove oxygen deficit

•Oxygen is required to get rid of accumulated lactic acidlactic acid

•Increasing acidity (from lactic acid) and lack of ATP causes the muscle to contract less


ATP causes the muscle to contract less

Types of Muscle Contractions

•Isotonic contractions•Myofilaments are able to slide past each other during contractionsg

•The muscle shortens and movement occursE l b di th k t ti th•Example: bending the knee; rotating the arm

•Isometric contractions•Tension in the muscles increasesTh l i bl t h t d•The muscle is unable to shorten or produce movement


•Example: push against a wall with bent elbows

Muscle Tone

•Some fibers are contracted even in a relaxed muscle

•Different fibers contract at different times toDifferent fibers contract at different times to provide muscle tone and to be constantly readyready


Effect of Exercise on Muscles

•Exercise increases muscle size, strength, and endurance•Aerobic (endurance) exercise (bikingAerobic (endurance) exercise (biking, jogging) results in stronger, more flexible muscles with greater resistance to fatiguemuscles with greater resistance to fatigue•Makes body metabolism more efficient•Improves digestion, coordination

•Resistance (isometric) exercise (weight•Resistance (isometric) exercise (weight lifting) increases muscle size and strength


Type I fibers Type II a fibers Type II x fibers Type II b fibers

Contraction time Slow Moderately Fast Fast Very fast

Size of motor neuron Small Medium Large Very large

Resistance to fatigue High Fairly high Intermediate Lowg g y g

Activity Used for Aerobic Long-term anaerobic Short-term anaerobic Short-term anaerobic

Maximum duration of use Hours <30 minutes <5 minutes <1 minuteuse

Power produced Low Medium High Very high

Mitochondrial density Very High High Medium Low

Capillary density High Intermediate Low Low

Oxidative capacity High High Intermediate Low

Glycolytic capacity Low High High HighGlycolytic capacity Low High High High

Major storage fuel Triglycerides Creatine phosphate, glycogen

ATP, Creatine phosphate, glycogen (little)

ATP, Creatine phosphate

Note Consume lactic acid Produce lactic acid and Creatine phosphate

Consume Creatine phosphate

Consume Creatine phosphate

Myosin heavy chain


Myosin heavy chain,human genes MYH7 MYH2 MYH1 MYH4

Five Golden Rules of Skeletal Muscle Activity1 With a few exceptions all skeletal muscles1. With a few exceptions, all skeletal muscles

cross at least one joint.2 T i ll th b lk f k l t l l li2. Typically, the bulk of a skeletal muscle lies

proximal to the joint crossed.3. All skeletal muscles have at least two

attachments: the origin and the insertion.attachments: the origin and the insertion.4. Skeletal muscles can only pull; they never

pushpush.5. During contraction, a skeletal muscle


insertion moves toward the origin.

Muscles and Body Movements

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

•Muscles are attached to at least two pointsMuscles are attached to at least two points•Origin

•Attachment to a moveable bone•InsertionInsertion

•Attachment to an immovable bone


Musclecontracting

Origin

Brachialis

Tendon


Insertion

Types of Body Movements

•FlexionD th l f th j i t•Decreases the angle of the joint

•Brings two bones closer togetherg g•Typical of bending hinge joints like knee and elbow or ball and socket joints like the hipelbow or ball-and-socket joints like the hip

•Extension•Opposite of flexion•Increases angle between two bones•Increases angle between two bones•Typical of straightening the elbow or knee


•Extension beyond 180° is hypertension


•Rotation•Movement of a bone around its longitudinal axisaxis

•Common in ball-and-socket joints•Example is when you move atlas around the dens of axis (shake your head “no”)( y )



•Abduction•Movement of a limb away from the midline

Adduction•Adduction•Opposite of abduction•Movement of a limb toward the midline



•Circumduction•Combination of flexion, extension, abduction, and adductionand adduction

•Common in ball-and-socket joints


Special Movements

•Dorsiflexion•Lifting the foot so that the superior surface approaches the shin (toward the dorsum)approaches the shin (toward the dorsum)

•Plantar flexion•Depressing the foot (pointing the toes)•“Planting” the foot toward the solePlanting the foot toward the sole


Special Movements

•Inversion•Turn sole of foot medially

Eversion•Eversion•Turn sole of foot laterally


Special Movements

•Supination•Forearm rotates laterally so palm faces anteriorlyanteriorly

•Radius and ulna are parallel•Pronation

•Forearm rotates medially so palm facesForearm rotates medially so palm faces posteriorly R di d l h th lik X•Radius and ulna cross each other like an X


Special Movements

•Opposition•Move thumb to touch the tips of other fingers on the same handfingers on the same hand


Types of Muscles

•Prime mover—muscle with the major responsibility for a certain movement

•Antagonist—muscle that opposes or reversesAntagonist muscle that opposes or reverses a prime moverS i t l th t id i i•Synergist—muscle that aids a prime mover in a movement and helps prevent rotation

•Fixator—stabilizes the origin of a prime mover


(a) A muscle that crosses on the anterior side of a joint produces flexion*

Example:PectoralisPectoralis major(anterior view)


(b) A muscle that crosses on the posterior side of a joint produces extension*

Example:Latissimusd idorsi(posteriorview)


(c) A muscle that crosses on the lateral side of a joint produces abduction

Example:Medial deltoid(anterolateralview)


(d) A muscle that crosses on the medial side of a joint produces adduction

E lExample:Teres major(posterolateralview)


Naming Skeletal Muscles

•By direction of muscle fibers•Example: Rectus (straight)

By relative size of the muscle•By relative size of the muscle•Example: Maximus (largest)



•By location of the muscle•Example: Temporalis (temporal bone)

By number of origins•By number of origins•Example: Triceps (three heads)



•By location of the muscle’s origin and insertion•Example: Sterno (on the sternum)

By shape of the muscle•By shape of the muscle•Example: Deltoid (triangular)

•By action of the muscleExample: Flexor and extensor (flexes or•Example: Flexor and extensor (flexes or extends a bone)


Orbicularis orisDeltoidPectoralis major

(d) Circular

(a) Convergent

Biceps brachii (d)(e) Multipennate

Rectus femoris

(a)(e)

(b)

Rectus femoris

(f) Bipennate(c)

(b) Fusiform (f) Bipennate( )

Sartorius (f) Extensor digitorum longus

(g)

© 2012 Pearson Education, Inc. Figure 6.15(g) Unipennate(c) Parallel

Head and Neck Muscles•Facial muscles

•Frontalis raises eyebrows•Frontalis—raises eyebrows•Orbicularis oculi—closes eyes, squints, blinks winksblinks, winks

•Orbicularis oris—closes mouth and protrudes the lipsp ot udes t e ps

•Buccinator—flattens the cheek, chews•Zygomaticus—raises corners of the mouthZygomaticus raises corners of the mouth

•Chewing muscles•Masseter closes the jaw and elevates•Masseter—closes the jaw and elevates mandible

•Temporalis—synergist of the masseter


Temporalis synergist of the masseter, closes jaw

Head and Neck Muscles

•Neck muscles•Platysma—pulls the corners of the mouth inferiorlyinferiorly

•Sternocleidomastoid—flexes the neck, t t th h drotates the head


CranialaponeurosisFrontalis

Orbicularisoculi

Temporalis

Occipitalisoculi

Zygomaticus

Occipitalis

O bi l i

BuccinatorMasseter

Orbicularisoris Sternocleidomastoid

PlatysmaTrapezius


Muscles of Trunk, Shoulder, Arm

•Anterior muscles•Pectoralis major—adducts and flexes the humerushumerus

•Intercostal muscles •External intercostals—raise rib cage during inhalationg

•Internal intercostals—depress the rib cage to move air out of the lungs when youto move air out of the lungs when you exhale forcibly


Clavicle

Deltoid

Sternum

Pectoralismajor

Bicepsbrachii

Brachialis

Brachio-di liradialis



•Muscles of the abdominal girdle•Rectus abdominis—flexes vertebral column and compresses abdominal contentsand compresses abdominal contents (defecation, childbirth, forced breathing)E t l bli fl t b l l•External oblique—flex vertebral column; rotate trunk and bend it laterally

•Internal oblique—flex vertebral column; rotate trunk and bend it laterallyrotate trunk and bend it laterally

•Transversus abdominis—compresses abdominal contents


abdominal contents

Pectoralismajormajor

RectusabdominisTransversusabdominisInternaloblique

ExternalExternalobliqueAponeurosisp



•Posterior muscles•Trapezius—elevates, depresses, adducts, and stabilizes the scapulaand stabilizes the scapula

•Latissimus dorsi—extends and adducts the hhumerus

•Erector spinae—back extensionp•Quadratus lumborum—flexes the spine laterallylaterally

•Deltoid—arm abduction



•Muscles that arise from the shoulder girdle and cross the shoulder joint to insert into the humerus include:•Pectoralis majorL ti i d i•Latissimus dorsi

•Deltoid

PLAY A&P Flix™: Muscles of the pectoral girdle

PLAY A&P Flix™: Muscles that act on the shoulder joint and humerus: An overview.

PLAY A&P Flix™: Muscles that cross the glenohumeral joint.

PLAY A&P Flix™: Muscles of the pectoral girdle.


PLAY A&P Flix™: Movement at the glenohumeral joint: An overview.

Occipital bone

Sternocleidomastoid

Trapezius Spine of scapulaDeltoid (cut)

Deltoid

TricepsbrachiibrachiiLatissimusdorsi

Olecranonprocess of

Humerus


process ofulna (deepto tendon)

(a)

C7T1

Erector spinaep• Iliocostalis• Longissimus• Spinalis

QuadratusIumborum


Muscles of the Upper Limb

•Biceps brachii—supinates forearm, flexes elbow

•Brachialis—elbow flexionBrachialis elbow flexion•Brachioradialis—weak muscle; elbow flexion•Triceps brachii—elbow extension (antagonist to biceps brachii)p )

PLAY A&P Flix™: The elbow joint and forearm: An overview.

&

PLAY A&P Flix™: Muscles of the elbow joint.


PLAY A&P Flix™: Movement at the elbow joint.

Clavicle

Deltoid

Sternum

Pectoralismajor

Bicepsbrachii

Brachialis

Brachio-di liradialis


Occipital bone

Sternocleidomastoid

Trapezius Spine of scapulaDeltoid (cut)

Deltoid

TricepsbrachiibrachiiLatissimusdorsi

Olecranonprocess of

Humerus


process ofulna (deepto tendon)

(a)

Muscles of the Upper Limb

•Muscles of the forearm, which insert on the h d b d th i thand bones and cause their movement include:

•Flexor carpi—wrist flexion•Flexor digitorum—finger flexion•Flexor digitorum—finger flexion•Extensor carpi—wrist extension•Extensor digitorum—finger extension

PLAY A&P Flix™: Muscles that act on the wrist and fingers:

PLAY A&P Flix™: Movements of the wrist and fingers (a).

PLAY A&P Flix : Muscles that act on the wrist and fingers: An overview.


PLAY A&P Flix™: Movements of the wrist and fingers (b).

Muscles of the Lower Limb

•Muscles causing movement at the hip joint include:•Gluteus maximus—hip extensionGluteus maximus hip extension•Gluteus medius—hip abduction, steadies

l i h lkipelvis when walking•Iliopsoas—hip flexion, keeps the upper body p p , p pp yfrom falling backward when standing erect

•Adductor muscles adduct the thighs•Adductor muscles—adduct the thighsPLAY A&P Flix™: Muscles that act on the hip joint and femur:

An overview


PLAY A&P Flix™: Movement at the hip joint: An overview.An overview.

Gluteus medius

Gluteus maximus

Adductormagnus

Iliotibial tract

Biceps femoris

SemitendinosusSemimembranosus

Hamstring group


Gastrocnemius

(a)

Posterior superioriliac spine

IIiac crest

p

Safe area inSafe area ingluteus medius

S i ti

Gluteus maximus

Sciatic nerve


12th rib12ththoracic vertebra

Iliac crestlliopsoas Psoas major

lliacus

Anterior superiorili i

5thlumbar vertebra

iliac spine

SartoriusAdd t

Rectus femoris

Vastus lateralis

ricep

s

Adductorgroup

Vastus medialisQua

dr

Patellarligament

Patella


g

(c)


•Muscles causing movement at the knee joint•Hamstring group—thigh extension and knee flexionflexion•Biceps femoris•Semimembranosus•SemitendinosusSemitendinosus


Gluteus medius

Gluteus maximus

Adductormagnus

Iliotibial tract

Biceps femoris

SemitendinosusSemimembranosus

Hamstring group


Gastrocnemius

(a)


•Muscles causing movement at the knee joint•Sartorius—flexes the thighQuadriceps group extends the knee•Quadriceps group—extends the knee•Rectus femoris•Vastus muscles (three)

PLAY A&P Flix™: Muscles that cross the knee joint: An overview.


12th rib12ththoracic vertebra

Iliac crestlliopsoas Psoas major

lliacus

Anterior superiorili i

5thlumbar vertebra

iliac spine

SartoriusAdd t

Rectus femoris

Vastus lateralis

ricep

s

Adductorgroup

Vastus medialisQua

dr

Patellarligament

Patella


g

(c)

Inguinal

Add t

Inguinalligament

Sartorius

Adductormuscles

Vastus

Sartorius

lateralis

© 2012 Pearson Education, Inc. Figure 6.20d(d)


•Muscles causing movement at ankle and footTibi li t i d ifl i f t i i•Tibialis anterior—dorsiflexion, foot inversion

•Extensor digitorum longus—toe extension g gand dorsiflexion of the foot

•Fibularis muscles plantar flexion foot•Fibularis muscles—plantar flexion, foot eversion

•Soleus—plantar flexionPLAY A&P Flix™: Muscles that act on the ankle and foot:

PLAY A&P Flix™: Posterior muscles that act on the ankle and foot.An overview.


PLAY A&P Flix™: Movements of the ankle and foot.

Fibularis longus

Tibia

Tibialis anteriorExtensor digitorumlongus

TibiaSoleus

Fibularis brevis

Fibularis tertius

longus


Gastrocnemius

Soleus

Calcaneal (Achilles)tendontendon

Medial malleolusLateralmalleolus


Facial• Temporalis

Facial• Frontalis• Orbicularis oculi• Zygomaticus

• Masseter

Shoulder• Trapezius

• Deltoid

• Orbicularis orisNeck• Platysma• SternocleidomastoidThorax• Pectoralis minor

Arm• Triceps brachii• Biceps brachii• Brachialis

• Pectoralis major• Serratus anterior

• Intercostals

Abdomen• Rectus abdominis

Forearm• Brachioradialis• Flexor carpi radialis

Pelvis/thigh• lliopsoas

• External oblique• Internal oblique• Transversus abdominis

Thigh (Quadriceps)• Rectus femoris• Vastus lateralis

Thigh• Sartorius• Adductor muscle

• Gracilis

• Vastus medialis

Leg• Fibularis longus

Leg• Extensor digitorum longus

• Tibialis anterior

Leg• Gastrocnemius

• Soleus


Neck• Occipitalis

Arm

• Sternocleidomastoid

• Trapezius

Shoulder/Back• DeltoidArm

• Triceps brachii• BrachialisForearm• Brachioradialis• Extensor carpi radialis

longus

• Latissimus dorsi

longus• Flexor carpi ulnaris• Extensor carpi ulnaris• Extensor digitorum

Hip• Gluteus medius

• Gluteus maximus

lliotibial tract Thigh• Adductor muscle• Hamstrings:

Leg

gBiceps femorisSemitendinosusSemimembranosus

• Gastrocnemius

• Soleus

• Fibularis longus


Calcaneal(Achilles)tendon

D lt idDeltoidmuscle

Humerus


Posterior superioriliac spine

IIiac crest

p

Safe area inSafe area ingluteus medius

S i ti

Gluteus maximus

Sciatic nerve


Inguinal

Add t

Inguinalligament

Sartorius

Adductormuscles

Vastus

Sartorius

lateralis

© 2012 Pearson Education, Inc. Figure 6.20d(d)

Superficial Anterior Muscles of the Body


Table 6.3 (1 of 3)



Table 6.3 (2 of 3)



Table 6.3 (3 of 3)

Superficial Posterior Muscles of the Body


Table 6.4 (1 of 3)



Table 6.4 (2 of 3)



Table 6.4 (3 of 3)

the muscular system -...

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