8 - 1 chapter 8 muscular system. 8 - 2 introduction: a.all movements require muscle which are organs...

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Chapter 8Muscular System

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Introduction:Introduction:

A. All movements require muscle which are organs using chemical energy to

contract.

B. The three types of muscle in the body are skeletal, smooth, and cardiac muscle.

C. This chapter focuses on skeletal muscle.

CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Structure of a Skeletal MuscleStructure of a Skeletal Muscle

A.A. Each muscle is an organ, comprised of Each muscle is an organ, comprised of skeletal muscle tissue, connective skeletal muscle tissue, connective

tissues, tissues, nervous tissue, and blood.nervous tissue, and blood.


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B.B. Connective Tissue Coverings Connective Tissue Coverings 1.1. Layers of dense connective Layers of dense connective tissue, tissue, called called fascia,fascia, surround and surround and separate separate each muscle.each muscle.

2.2. This connective tissue extends This connective tissue extends beyond beyond the ends of the muscle and the ends of the muscle and gives rise to gives rise to tendonstendons that are fused to the that are fused to the periosteum periosteum of bones.of bones.


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3.3. Sometimes muscles are connected to Sometimes muscles are connected to each other by broad sheets of each other by broad sheets of connective tissue called connective tissue called aponeuroses.aponeuroses.

4.4. The layer of connective tissue around The layer of connective tissue around each whole muscle is the each whole muscle is the epimysiumepimysium; ; the the perimysiumperimysium surrounds individual surrounds individual bundles (bundles (fascicles)fascicles) within each muscle; within each muscle; and each muscle cell (fiber) is covered and each muscle cell (fiber) is covered by a connective tissue layer called by a connective tissue layer called endomysium.endomysium.


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Study AnalogyStudy Analogy

Pretend you are going to play a joke on Pretend you are going to play a joke on someonesomeone

and give them 100 pencils. The pencils will and give them 100 pencils. The pencils will represent muscle fibers. First you wrap each represent muscle fibers. First you wrap each individual pencil in tissue paper (dense individual pencil in tissue paper (dense

tissue paper of course!). This would be tissue paper of course!). This would be endomysium.endomysium. Then you take about 10 Then you take about 10 pencils in a bundle (a pencils in a bundle (a fasciclefascicle) and wrap ) and wrap them in paper (them in paper (perimysiumperimysium). After that you ). After that you take all the bundles and wrap them in gift take all the bundles and wrap them in gift wrap (wrap (epimysiumepimysium). But you are going to mail ). But you are going to mail this joke, so you also have to wrap it in this joke, so you also have to wrap it in brown paper representing the brown paper representing the fasciafascia..


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C.C. Skeletal Muscle Fibers Skeletal Muscle Fibers

1.1. Each muscle Each muscle fiberfiber is a single, long, is a single, long, cylindrical muscle cell.cylindrical muscle cell.

2.2. Beneath the Beneath the sarcolemmasarcolemma (cell (cell membrane) lies membrane) lies sarcoplasmsarcoplasm

(cytoplasm) (cytoplasm) with many mitochondria and with many mitochondria and nuclei; the nuclei; the sarcoplasm contains sarcoplasm contains myofibrils.myofibrils.


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a.a. Thick filaments of myofibrils Thick filaments of myofibrils are are made up of the protein made up of the protein myosinmyosin..

b.b. Thin filaments of myofibrils Thin filaments of myofibrils are are made up of the protein made up of the protein actinactin..

c.c. The organization of these The organization of these filaments produces filaments produces

striations.striations.


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3.3. A A sarcomere sarcomere extends from Z line to extends from Z line to Z Z line.line.

a. a. I bandsI bands (light bands) made up of (light bands) made up of

actin filaments are anchored actin filaments are anchored to Z to Z lines.lines.

b.b. A bandsA bands (dark bands) are (dark bands) are made made up of overlapping thick and up of overlapping thick and thin thin filaments.filaments.

c.c. In the center of A bands is an In the center of A bands is an H H zone, consisting of myosin zone, consisting of myosin

filaments only.filaments only.

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4.4. Beneath the sarcolemma of a muscle Beneath the sarcolemma of a muscle fiber lies the fiber lies the sarcoplasmic sarcoplasmic

reticulumreticulum (endoplasmic (endoplasmic reticulum), which is reticulum), which is associated associated with with transverse (T) tubulestransverse (T) tubules (invaginations of the sarcolemma).(invaginations of the sarcolemma).


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a.a. Each T tubule lies between two Each T tubule lies between two cisternae of the sarcoplasmic cisternae of the sarcoplasmic reticulum and is open to the reticulum and is open to the outside of the muscle fiber.outside of the muscle fiber.

b.b. The sarcoplasmic reticulum and The sarcoplasmic reticulum and transverse tubules activate the transverse tubules activate the muscle contraction mechanism muscle contraction mechanism when the fiber is stimulated. when the fiber is stimulated.


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D.D. Neuromuscular JunctionNeuromuscular Junction 1.1. The site where the motor neuron and The site where the motor neuron and muscle fiber meet is the neuromuscular muscle fiber meet is the neuromuscular junction.junction.a.a. The muscle fiber membrane The muscle fiber membrane forms forms a a motor end platemotor end plate in which in which the sarcolemma is the sarcolemma is tightly folded tightly folded and where nuclei and and where nuclei and mitochondria are abundant.mitochondria are abundant.b.b. The cytoplasm of the motor The cytoplasm of the motor neuron contains numerous neuron contains numerous mitochondria and mitochondria and synapticsynaptic vesicles vesicles storing storing neurotransmitters.neurotransmitters.


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E.E. Motor Units Motor Units

1.1. A motor neuron and the A motor neuron and the muscle muscle fibers it controls make fibers it controls make up a motor up a motor unit; when stimulated unit; when stimulated to do so, to do so, the muscle fibers the muscle fibers of the motor of the motor unit unit contract all at once. contract all at once.


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Skeletal Muscle ContractionSkeletal Muscle Contraction A. Muscle contraction involves several A. Muscle contraction involves several

components that result in the components that result in the shorteningshortening

of sarcomeres,of sarcomeres, and the pulling of and the pulling of thethe

muscle against its attachments.muscle against its attachments.

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B.B. Role of Myosin and Actin Role of Myosin and Actin

1.1. MyosinMyosin consists of two twisted strands consists of two twisted strands with with globular cross-bridges projected outward alongglobular cross-bridges projected outward along

the strands.the strands.2.2. ActinActin is a globular protein with myosin binding is a globular protein with myosin binding

sites; sites; tropomysosintropomysosin and and troponintroponin are two proteins are two proteins associated with the surface of the actin filaments.associated with the surface of the actin filaments.

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3.3. According to the sliding filament theory According to the sliding filament theory of muscle contraction, the myosin of muscle contraction, the myosin crossbridgecrossbridge attaches to the binding site attaches to the binding site on the actin filament and bends, pulling on the actin filament and bends, pulling on the actin filament; it then releases on the actin filament; it then releases and attaches to the next binding site on and attaches to the next binding site on the actin, pulling again.the actin, pulling again.

4.4. Energy from the conversion of ATP to Energy from the conversion of ATP to ADP is provided to the cross-bridges ADP is provided to the cross-bridges from the enzyme ATPase, causing them from the enzyme ATPase, causing them to be in a “cocked” position. to be in a “cocked” position.


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C.C. Stimulus for ContractionStimulus for Contraction 1.1. The motor neuron must release the The motor neuron must release the

neurotransmitter neurotransmitter acetylcholine from its acetylcholine from its synaptic vesicles synaptic vesicles into the synaptic cleft into the synaptic cleft in order to in order to initiate a muscle contraction.initiate a muscle contraction.

2.2. Protein receptors in the motor end Protein receptors in the motor end plate plate detect the neurotransmitters, and a detect the neurotransmitters, and a

muscle impulse spreads over muscle impulse spreads over the surface the surface of the sarcolemma and into of the sarcolemma and into the T the T tubules, where it reaches the tubules, where it reaches the

sarcoplasmic reticulum.sarcoplasmic reticulum.

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3.3. Upon receipt of the muscle impulse, the Upon receipt of the muscle impulse, the sarcoplasmic reticulum releases its sarcoplasmic reticulum releases its stored calcium to the sarcoplasm of the stored calcium to the sarcoplasm of the muscle fiber.muscle fiber.4.4. The high concentration of calcium in the The high concentration of calcium in the

sarcoplasm interacts with the sarcoplasm interacts with the troponin and tropomyosin molecules, troponin and tropomyosin molecules, which which move aside, exposing the myosin move aside, exposing the myosin binding binding sites on the actin filaments.sites on the actin filaments.

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5.5. Myosin cross-bridges now bind and Myosin cross-bridges now bind and pull pull on the actin filaments, causing the on the actin filaments, causing the

sarcomeres to shorten.sarcomeres to shorten.6.6. After the nervous impulse has been After the nervous impulse has been

received, acetylcholinesterase rapidly received, acetylcholinesterase rapidly decomposes the acetylcholine.decomposes the acetylcholine.

7.7. Then, calcium is returned to the Then, calcium is returned to the sarcoplasmic reticulum, and the sarcoplasmic reticulum, and the linkages between myosin and actin are linkages between myosin and actin are broken. broken.

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Study Analogy: Study Analogy: Think of a very familiar love story. Think of a very familiar love story. The actin and myosin are in love and would love to The actin and myosin are in love and would love to bind (keep it clean, think kiss). However, the actin is bind (keep it clean, think kiss). However, the actin is being guarded by the troponin and tropomysin (T-T being guarded by the troponin and tropomysin (T-T complex), perhaps they are her parents or guardians? complex), perhaps they are her parents or guardians? But someone is looking out for the love birds, maybe But someone is looking out for the love birds, maybe a fairy godmother? They send a messenger in the a fairy godmother? They send a messenger in the form of a nerve impulse. This messenger isn’t form of a nerve impulse. This messenger isn’t someone allowed in the house, so they send a second someone allowed in the house, so they send a second messenger (acetylocholinesterase) by way of the messenger (acetylocholinesterase) by way of the trusty T-tubules. This messenger releases a trusty T-tubules. This messenger releases a distractor (aka calcium). Pretend this is a belly distractor (aka calcium). Pretend this is a belly dancer or someone from Publisher’s clearing house or dancer or someone from Publisher’s clearing house or some other such distractionsome other such distraction. .


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While the T-T complex is so occupied, actin While the T-T complex is so occupied, actin and myosin are free to bind. Of course this and myosin are free to bind. Of course this takes a lot of energy (who said love was takes a lot of energy (who said love was easy?) But the messenger has only been paid easy?) But the messenger has only been paid for so long (destroyed by for so long (destroyed by acetylcholinesterase) and the distractor can acetylcholinesterase) and the distractor can only dance (or whatever) for so long and has only dance (or whatever) for so long and has to leave. (calcium returns to sarcoplasmic to leave. (calcium returns to sarcoplasmic reticulum). Thus the linkages are broken and reticulum). Thus the linkages are broken and they cannot live happily every after. But wait, they cannot live happily every after. But wait, another impulse may come along at any time!another impulse may come along at any time!


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D.D. Energy Sources for ContractionEnergy Sources for Contraction 1. 1. Energy for contraction comes Energy for contraction comes

from molecules of from molecules of ATPATP. This . This chemical is in limited supply chemical is in limited supplyand so must often be and so must often be

regeneratedregenerated2.2. Creatine phosphateCreatine phosphate, which , which

stores stores excess energy released excess energy released by the by the mitochondria, is mitochondria, is present topresent to

regenerate ATP from ADP and regenerate ATP from ADP and phosphate.phosphate.

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3.3. Whenever the supply of ATP Whenever the supply of ATP is is sufficient,creatine sufficient,creatine phosphokinase phosphokinase promotes the promotes the synthesis of creatine synthesis of creatine phosphate.phosphate.

4.4. As ATP decomposes, the As ATP decomposes, the energy energy from creatine from creatine phosphate can be phosphate can be transferred to transferred to ADP molecules, ADP molecules, converting them converting them back to ATP. back to ATP.

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E.E. Oxygen Supply and Cellular RespirationOxygen Supply and Cellular Respiration 1.1. The early phase of cellular respirationThe early phase of cellular respiration

yields few molecules of ATP, so muscle yields few molecules of ATP, so muscle has a high requirement for oxygen, has a high requirement for oxygen,

which enables the complete breakdownwhich enables the complete breakdown of glucose in the mitochondria.of glucose in the mitochondria.

2.2. Hemoglobin in red blood cells carries Hemoglobin in red blood cells carries oxygen to muscle.oxygen to muscle.

3.3. The pigment myoglobin stores oxygen The pigment myoglobin stores oxygen in muscle tissue. in muscle tissue.

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F.F. Oxygen DebtOxygen Debt1.1. During rest or moderate activity, there During rest or moderate activity, there

is enough oxygen to support aerobic is enough oxygen to support aerobic respiration.respiration.

2.2. Oxygen deficiency may develop during Oxygen deficiency may develop during strenuous exercise, and lactic acid strenuous exercise, and lactic acid accumulates as an end product of accumulates as an end product of anaerobic respiration.anaerobic respiration.a.a. Lactic acidLactic acid diffuses out of muscle diffuses out of muscle

cells and is carried in the cells and is carried in the bloodstream to the liver.bloodstream to the liver.

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3.3. Oxygen debt refers to the amount of Oxygen debt refers to the amount of oxygen that liver cells require to oxygen that liver cells require to convert the accumulated lactic acid into convert the accumulated lactic acid into glucose, glucose, PLUS PLUS the amount that muscle the amount that muscle

cells cells

need to resynthesize ATP and need to resynthesize ATP and creatine phosphate to their original creatine phosphate to their original concentrations.concentrations.

4.4. Repaying oxygen debt may take several Repaying oxygen debt may take several hours, to days.hours, to days.

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G.G. Muscle FatigueMuscle Fatigue1.1. When a muscle loses its ability to When a muscle loses its ability to

contract during strenuous contract during strenuous exercise, it is exercise, it is referred to as fatigue.referred to as fatigue.

2.2. Muscle fatigue usually arises from Muscle fatigue usually arises from the the accumulation of lactic acid in the accumulation of lactic acid in the

muscle.muscle.a.a. A lowered pH as a result of A lowered pH as a result of

accumulated lactic acid preventsaccumulated lactic acid prevents the muscle from contracting.the muscle from contracting.

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3.3. A A muscle crampmuscle cramp occurs due to a occurs due to a lack of lack of ATP required to return ATP required to return calcium ions calcium ions back to the back to the sarcoplasmic reticulum so sarcoplasmic reticulum so muscle muscle fibers can relax. fibers can relax.


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H.H. Heat ProductionHeat Production

1.1. Contraction of skeletal muscle Contraction of skeletal muscle represents an important represents an important

source of heat source of heat for the body.for the body.

2.2. Much of the energy produced Much of the energy produced through through the reactions of cellular the reactions of cellular respiration is respiration is lost as heat (another lost as heat (another

source of heat for source of heat for the body).the body).

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Muscular ResponsesMuscular Responses A. One method of studying muscle A. One method of studying muscle

function is to remove a single fiber function is to remove a single fiber and and connect it to a device that records its connect it to a device that records its

responses to electrical responses to electrical stimulation.stimulation.

B. B. Threshold StimulusThreshold Stimulus1. A muscle fiber remains1. A muscle fiber remains

unresponsive to stimulation unresponsive to stimulation unless the stimulus is of a unless the stimulus is of a

certain certain strength, called the threshold strength, called the threshold

stimulus. stimulus.

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C.C. All-or-None ResponseAll-or-None Response

1.1. When a muscle fiber contracts, it When a muscle fiber contracts, it contracts to its full extent (all-contracts to its full extent (all-

or-none or-none response); it cannot response); it cannot contract partially. contract partially.

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D.D. Recording a Muscular Contraction Recording a Muscular Contraction

1.1. A A myogrammyogram is the recording of an is the recording of an electrically-stimulated muscle electrically-stimulated muscle contraction.contraction.

2.2. A single, short contraction involving A single, short contraction involving only a few motor units is referred to as a only a few motor units is referred to as a twitch.twitch.


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3.3. The time delay between when The time delay between when the the stimulus is applied and when stimulus is applied and when the the muscle contracts is called muscle contracts is called thethe

latent periodlatent period, which is less , which is less than 0.01 than 0.01 second. second.

4.4. The latent period is followed The latent period is followed by a by a period of contraction and a period of contraction and a period of period of relaxation. relaxation.

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E.E. Summation Summation

1.1. A muscle fiber receiving a series of A muscle fiber receiving a series of stimuli of increasing stimuli of increasing

frequency reaches frequency reaches a point when it is a point when it is unable to relax unable to relax completely and completely and the force of individual the force of individual twitches combine twitches combine by the process of by the process of summation.summation.

2.2. If the sustained contraction lacks any If the sustained contraction lacks any relaxation, it is called a relaxation, it is called a tetanic tetanic

contraction.contraction.

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F.F. Recruitment of Motor Units Recruitment of Motor Units

1.1. An increase in the number of An increase in the number of activated activated motor units within a muscle motor units within a muscle at higher at higher intensities of intensities of stimulation is called stimulation is called recruitment.recruitment.

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G.G. Sustained ContractionsSustained Contractions

1.1. Summation and recruitment togetherSummation and recruitment togethercan produce a sustained contraction of can produce a sustained contraction of increasing strength.increasing strength.

2.2. Muscle Muscle tonetone is achieved by a is achieved by a continuous continuous state of sustained contraction of state of sustained contraction of motor motor units within a muscle. units within a muscle.

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Smooth MusclesSmooth Muscles

A.A. Smooth Muscle FibersSmooth Muscle Fibers

1.1. Smooth muscle cells are Smooth muscle cells are elongated with tapered elongated with tapered

ends, lack ends, lack striations, and have a striations, and have a relatively relatively undeveloped undeveloped sarcoplasmic sarcoplasmic reticulum.reticulum.


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2.2. Multiunit smooth muscleMultiunit smooth muscle and and visceral musclevisceral muscle are two types are two types

of of smooth muscles.smooth muscles.

a.a. In multiunit smooth muscle, In multiunit smooth muscle, such such as in the blood vessels and as in the blood vessels and iris of iris of the eye, fibers occur the eye, fibers occur separately separately rather than as rather than as sheets.sheets.


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b.b. Visceral smooth muscle Visceral smooth muscle occurs in occurs in sheets and is found in sheets and is found in the walls of the walls of hollow organs; these hollow organs; these fibers can fibers can stimulate one stimulate one another and display another and display rhythmicity, and are thus rhythmicity, and are thus

responsible for peristalsis in responsible for peristalsis in hollow organs and tubes. hollow organs and tubes.


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B.B. Smooth Muscle ContractionSmooth Muscle Contraction1.1. The myosin-binding-to-actin The myosin-binding-to-actin

mechanism is the mostly same for mechanism is the mostly same for smooth muscles and skeletal smooth muscles and skeletal muscles.muscles.

2.2. Both acetylcholine and Both acetylcholine and norepinephrine stimulate and norepinephrine stimulate and inhibit smooth muscle inhibit smooth muscle contraction, depending on the contraction, depending on the target muscle.target muscle.


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3.3. Hormones can also stimulate or Hormones can also stimulate or inhibit inhibit contraction.contraction.

4.4. Smooth muscle is slower to contract Smooth muscle is slower to contract and relax than is skeletal and relax than is skeletal

muscle, but muscle, but can contract longer can contract longer using the same using the same amount of ATP. amount of ATP.


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Cardiac MuscleCardiac Muscle

A.A. The mechanism of contraction The mechanism of contraction in in cardiac muscle is cardiac muscle is essentially the essentially the same as that same as that for skeletal and for skeletal and smooth smooth muscle, but with some muscle, but with some differences. differences.

B.B. Cardiac muscle has transverse Cardiac muscle has transverse tubules that supply extra tubules that supply extra

calcium, calcium, and can thus contract for and can thus contract for longer longer periods.periods.


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C.C. Complex membrane junctions, called Complex membrane junctions, called intercalated disksintercalated disks, join cells and , join cells and transmit the force of contraction from transmit the force of contraction from one cell to the next, as well as aid in one cell to the next, as well as aid in

the the rapid transmission of impulses rapid transmission of impulses throughout the heart.throughout the heart.

D.D. Cardiac muscle is self-exciting and Cardiac muscle is self-exciting and rhythmic, and the whole structure rhythmic, and the whole structure contracts as a unit. contracts as a unit.


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Skeletal Muscle ActionsSkeletal Muscle Actions A.A. Origin and InsertionOrigin and Insertion

1.1. The immovable end of a The immovable end of a muscle muscle is the is the originorigin, while the , while the movable movable end is the insertion; end is the insertion; contraction contraction pulls the pulls the insertioninsertion toward the toward the origin.origin.

2.2. Some muscles have more Some muscles have more than than one insertion or origin.one insertion or origin.


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B.B. Interaction of Skeletal MusclesInteraction of Skeletal Muscles

1.1. Of a group of muscles, the Of a group of muscles, the one one doing the majority of doing the majority of the work is the work is the the prime moverprime mover..

2.2. Helper muscles are called Helper muscles are called synergistssynergists; opposing ; opposing

muscles are muscles are called called antagonistsantagonists. .


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Major Skeletal MusclesMajor Skeletal Muscles

A.A. Muscles are named according to Muscles are named according to any any of the following criteria: size, of the following criteria: size, shape, shape, location, action, number of location, action, number of

attachments, or attachments, or direction of its fibers.direction of its fibers.


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B.B. Muscles of Facial ExpressionMuscles of Facial Expression 1.1. Muscles of facial expression Muscles of facial expression attach to underlying bones and attach to underlying bones and overlying connective tissue of overlying connective tissue of skin, and are responsible for skin, and are responsible for the variety of facial expressions the variety of facial expressions possible in the human face.possible in the human face.2.2. Major muscles includeMajor muscles include

epicranius,epicranius, orbicularis oculi,orbicularis oculi, orbicularis orbicularis oris, buccinator,oris, buccinator, zygomatigus,zygomatigus,


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C.C. Muscles of MasticationMuscles of Mastication 1.1. Chewing movements include Chewing movements include

up up and down as well as side-to-and down as well as side-to-side side grinding motions of muscles grinding motions of muscles

attached to the skull attached to the skull and lower and lower jaw.jaw.

2.2. Chewing muscles include Chewing muscles include masseter and temporalis. masseter and temporalis.


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D.D. Muscles that Move the HeadMuscles that Move the Head

1.1. Paired muscles in the neck and back Paired muscles in the neck and back flex, extend, and turn the head.flex, extend, and turn the head.

2. 2. Major muscles includeMajor muscles include sternocleidomastoid, splenius capitis, and sternocleidomastoid, splenius capitis, and

semispinalis capitis.semispinalis capitis.


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E.E. Muscles that Move the Pectoral GirdleMuscles that Move the Pectoral Girdle

1.1. The chest and shoulder muscles The chest and shoulder muscles move move the scapula.the scapula.

2.2. Major muscles include Major muscles include trapezius,trapezius,

rhomboideus major,levator scapulae,rhomboideus major,levator scapulae,

serratus anterior, and pectoralisserratus anterior, and pectoralis

minor. minor.


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F.F. Muscles that Move the ArmMuscles that Move the Arm 1.1. Muscles connect the arm to the Muscles connect the arm to the

pectoral pectoral girdle, ribs, and vertebral girdle, ribs, and vertebral column, column, making the arm freely making the arm freely movable.movable.

2.2. Flexors include theFlexors include the coracobrachialis and pectoralis major.coracobrachialis and pectoralis major.


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3.3. Extensors Extensors include the teres major include the teres major

and latissimus dorsi.and latissimus dorsi.

4.4. AbductorsAbductors include the include the

supraspinatus and the deltoid.supraspinatus and the deltoid.

5.5. RotatorsRotators are the subscapularis, are the subscapularis,

infraspinatus, and teres minor. infraspinatus, and teres minor.


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G.G. Muscles that Move the ForearmMuscles that Move the Forearm 1.1. These muscles arise These muscles arise

from the from the humerus or humerus or pectoral girdle and pectoral girdle and connect to the ulna and radius.connect to the ulna and radius.

2.2. Flexors are the biceps brachii,Flexors are the biceps brachii,

brachialis,andbrachialis,and

brachioradialis.brachioradialis.


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3.3. An An extensorextensor is the triceps is the triceps

brachii muscle.brachii muscle.

4.4. Rotators include the supinator, Rotators include the supinator,

pronator teres, and pronator quadratus. pronator teres, and pronator quadratus.


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H.H. Muscles that Move the Wrist, Hand, and Muscles that Move the Wrist, Hand, and FingersFingers

1.1. Movements of the hand are caused by Movements of the hand are caused by muscles originating from the distal muscles originating from the distal humerus, and the radius and ulna.humerus, and the radius and ulna.

2.2. Flexors include the flexor carpiFlexors include the flexor carpi radialis, flexor carpi ulnaris,radialis, flexor carpi ulnaris, palmaris longus, and flexor digitorum palmaris longus, and flexor digitorum

profundus.profundus.


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3.3. Extensors include the extensor carpiExtensors include the extensor carpi

radialis longus, extensor carpi radialisradialis longus, extensor carpi radialis

brevis, extensor carpi ulnaris,brevis, extensor carpi ulnaris,

and extensor digitorum.and extensor digitorum.


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I.I. Muscles of the Abdominal WallMuscles of the Abdominal Wall 1.1. This group of muscles connects the rib This group of muscles connects the rib

cage and vertebral column to the pelvic cage and vertebral column to the pelvic girdle.girdle.a.a. A band of tough connective A band of tough connective

tissue, the linea alba, extending tissue, the linea alba, extending from the xiphoid process to the from the xiphoid process to the symphysis pubis, serves as an symphysis pubis, serves as an attachment for certain abdominal attachment for certain abdominal wall muscles.wall muscles.


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2.2. These four muscles include:These four muscles include:

external oblique, internal oblique, external oblique, internal oblique, transverse abdominis, and transverse abdominis, and

rectus rectus abdominis. abdominis.


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J.J. Muscles of the Pelvic OutletMuscles of the Pelvic Outlet

1.1. The superficial urogenital The superficial urogenital diaphragm diaphragm fills the space within fills the space within the pubic arch, and the pubic arch, and the deeper pelvic the deeper pelvic diaphragm forms the diaphragm forms the floor of the floor of the pelvic cavity.pelvic cavity.

2.2. Pelvic diaphragm ncludes the Pelvic diaphragm ncludes the

levator ani.levator ani.


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3.3. Urogenital diaphragm: includes theUrogenital diaphragm: includes the

superficial transversus, perinei,superficial transversus, perinei,

bulbospongiosus, andbulbospongiosus, and

ischiocavernosus.ischiocavernosus.


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K.K. Muscles that Move the ThighMuscles that Move the Thigh

1.1. The muscles that move the thigh are The muscles that move the thigh are attached to the femur and to attached to the femur and to

the pelvic the pelvic girdle.girdle.

2.2. Anterior group includes Anterior group includes the the

psoas major and iliacus.psoas major and iliacus.


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3.3. Posterior group is made upPosterior group is made up

of the gluteus maximus, gluteus of the gluteus maximus, gluteus medius, medius, gluteus minimus, and tensor gluteus minimus, and tensor fasciae fasciae latae.latae.

4.4. Thigh adductors include the Thigh adductors include the

adductor longus, adductor magnus,adductor longus, adductor magnus,

and gracilis. and gracilis.


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L.L. Muscles that Move the LegMuscles that Move the Leg 1.1. This group connects the tibia or fibula This group connects the tibia or fibula to the femur or pelvic girdle.to the femur or pelvic girdle.2.2. Flexors are the biceps femoris,Flexors are the biceps femoris,

semitendinosus,semitendinosus, semimembranosus, semimembranosus, and sartorius.and sartorius.

3.3. An extensor is the quadruceps femorisAn extensor is the quadruceps femoris group made up of four parts: rectus group made up of four parts: rectus

femoris, vastus lateralis, vastus femoris, vastus lateralis, vastus medialis, and vastus intermedius.medialis, and vastus intermedius.


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M.M.Muscles that Move the Ankle, Foot, and Muscles that Move the Ankle, Foot, and ToesToes

1.1. Muscles that move the foot are Muscles that move the foot are attached to the femur, fibula, or attached to the femur, fibula, or tibia, and move the foot upward, tibia, and move the foot upward, downward, or in a turning downward, or in a turning motion.motion.

2.2. Dorsal flexors include the tibialisDorsal flexors include the tibialisanterior, peroneus tertius, and anterior, peroneus tertius, and extensor digitorum longus.extensor digitorum longus.


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3.3. Plantar flexors are the Plantar flexors are the gastrocnemiusgastrocnemius

soleus, and flexor digitorumsoleus, and flexor digitorum

longus.longus.

4.4. An invertor is the tibialis posterior.An invertor is the tibialis posterior.

5.5. An evertor An evertor is the peroneus longus. is the peroneus longus.


8 - 1 chapter 8 muscular system. 8 - 2 introduction: a.all movements require muscle which are organs...

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