Muscular System

How does a How does a muscle contractionmuscle contraction occur? occur?

What What actionaction does muscle perform? does muscle perform?

A. All movements require contraction of muscles.

B. 3 types of muscle skeletal, smooth, and cardiac

C. over 600 skeletal muscles in the body.

3 Types of Muscle Tissue

Skeletal muscleSkeletal muscle Cardiac muscleCardiac muscle Smooth muscleSmooth muscle

3 Types of Muscle Tissue Skeletal muscleSkeletal muscle

Tendons attach muscle to boneTendons attach muscle to bone striations (light & dark bands) visible with striations (light & dark bands) visible with

microscope microscope voluntary control of contraction & relaxationvoluntary control of contraction & relaxation

3 Types of Muscle Tissue

Cardiac muscleCardiac muscle striations alternating dark and light bandsstriations alternating dark and light bands involuntary control (no conscious involuntary control (no conscious

control)control) autorhythmic because of built in autorhythmic because of built in

pacemakerpacemaker

3 Types of Muscle Tissue Smooth muscleSmooth muscle

in walls of hollow organs -- blood vessels & in walls of hollow organs -- blood vessels & digestive organs (esophagus,stomach, digestive organs (esophagus,stomach, intestine)intestine)

nonstriated in appearancenonstriated in appearance involuntaryinvoluntary

Muscles do 2 things Muscles do 2 things 1. contract 2. relax1. contract 2. relax

How? chemical energy How? chemical energy changed into changed into mechanical energymechanical energy

Movement producedMovement produced

Functions of Muscle Tissue Produce body movementsProduce body movements Stabilize body positionsStabilize body positions Regulates organ volumesRegulates organ volumes

through smooth muscles called sphinctersthrough smooth muscles called sphincters

Functions of Muscle Tissue

Movement of substances w/in body regulated by Movement of substances w/in body regulated by musclesmuscles blood, lymph, urine, air, food and fluidsblood, lymph, urine, air, food and fluids

Produces heatProduces heat involuntary contractions of skeletal muscle involuntary contractions of skeletal muscle

(shivering)(shivering)

Directional Movements

Directional Movements-

Flexion- decreasing the angle between 2 bones (ex. Bicep)

extension- increasing the angle between 2 bones (ex.Tricep)

Directional Movements-

Dorsiflexion- decrease angle between foot and shin (tibia)

Plantar flexion- foot towards floor (ex. Standing on toes)

Directional Movements abduction- moving part away from midline

adduction- moving part toward midline

Directional Movements Rotation- turning from side to side (Movement around axis)

Circumduction- end part follows a circle (cone shaped motion)

Directional Movements Pronation- turning face down (palms down)

Supination- turning face up (palms up)

Directional Movements

Eversion- bottom of foot turned laterally

Inversion- bottom of foot turned medially

Directional Movements

Retraction- pulling part backward (chin back in)

Protraction- moving part forward (stick out chin)

Directional Movements

Elevation- raising part (ex. Shoulder shrug)

Depression- lowering a part

Directional Movements

Lateral Flexion- bending to your side

Lateral Extension- straighten back up

Directional Movements

describe movements

Origin and Insertion Origin and Insertion Origin- the attachment of a muscle’s tendon to Origin- the attachment of a muscle’s tendon to

a stationary bone usually proximala stationary bone usually proximalInsertion- the attachment of a muscles tendon Insertion- the attachment of a muscles tendon

to a movable bone usually distalto a movable bone usually distal

Origin- coracoid process of scapula

Insertion- tuberosity of radius

Skeletal Muscle made up of 3 tissuesSkeletal Muscle made up of 3 tissues

A.A. a muscle is an organ, made of skeletal a muscle is an organ, made of skeletal muscle tissuemuscle tissue, , connective tissuesconnective tissues, and , and nervous tissuenervous tissue..

Skeletal Muscle Organization

From big fibers to small fibers

Ex. Rope made up of string

Muscle Fascicle Muscle Fiber (cell) Myofibrils actin myosin

Connective Tissue Covers our MusclesConnective Tissue Covers our MusclesFasciaFascia- layers of dense connective tissue surrounds and separate - layers of dense connective tissue surrounds and separate

each muscle. (looks and feels like leather) each muscle. (looks and feels like leather)

Connective Tissue becomes Tendons Connective Tissue becomes Tendons

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

EpimysiumEpimysium- connective tissue that surrounds entire - connective tissue that surrounds entire muscle (saran wrap) muscle (saran wrap)

PPerimysiumerimysium connective tissue thatconnective tissue that surrounds bundles of surrounds bundles of

muscle fibers (muscle fibers (fascicles)fascicles) [tear chicken] [tear chicken]

EndomysiumEndomysium each individual muscle cell (fiber) is each individual muscle cell (fiber) is covered by this connective tissue [endo=inside] covered by this connective tissue [endo=inside]

8 - 31

describe movements

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Muscle Fibers are cells Muscle Fibers are cells

a a muscle fibermuscle fiber is a single, long, cylindrical is a single, long, cylindrical cellcell..

Muscle Fibers are specialized cells Muscle Fibers are specialized cells

The cell membrane of a muscle fiber is called the The cell membrane of a muscle fiber is called the SarcolemmaSarcolemma it contains: it contains:

Sarcoplasm, mitochondria, sarcoplasmic reticulum Sarcoplasm, mitochondria, sarcoplasmic reticulum and myofibrils and myofibrils

Skeletal Muscle Fiber (cell) Skeletal Muscle Fiber (cell)

SarcoplasmSarcoplasm- liquid interior of the muscle cell- liquid interior of the muscle cell

MitochondriaMitochondria- helps produce ATP - helps produce ATP

Sarcoplasmic Reticulum-Sarcoplasmic Reticulum- network of tubes that hold network of tubes that hold Calcium- when released causes muscle contraction Calcium- when released causes muscle contraction

Skeletal Muscle Fiber (cell) Skeletal Muscle Fiber (cell)

Myofibrils- are made up of smaller myofilaments

One of the myofilaments is thick and other one is thin

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

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

organization of filaments produces striations (stripes).organization of filaments produces striations (stripes).

Sarcomere Sarcomere Basic unit contraction. Basic unit contraction.

I bandsI bands (light bands) made up of (light bands) made up of onlyonly actinactin filaments filaments anchored to structure called “Z lines”anchored to structure called “Z lines”

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

Sarcomere Sarcomere microscopic contraction. microscopic contraction.

In the center of A bands (dark band) is an In the center of A bands (dark band) is an H zoneH zone, , consisting of consisting of myosin myosin filaments filaments only.only.

The H zone is a region near center of sarcomere. The H zone is a region near center of sarcomere.

Sarcomere- Box that contractsSarcomere- Box that contracts

goesgoes from from ZZ line to line to Z Z line line

Remember that by the word Remember that by the word ““ZZarcomerearcomereZZ””

sarcomere sarcomere II bands bands (l (lIIght bands) made up of ght bands) made up of onlyonly actinactin filaments filaments

anchored to Z lines. Actin think “act thin”anchored to Z lines. Actin think “act thin”AA bands bands (d (dAArk bands) overlapping thick and thin rk bands) overlapping thick and thin

filaments. (both myosin and actin filaments) that’s filaments. (both myosin and actin filaments) that’s why it’s dark [A band = length of Myosin]why it’s dark [A band = length of Myosin]

Beneath the sarcolemma lies the Beneath the sarcolemma lies the sarcoplasmic sarcoplasmic reticulumreticulum (holds calcium) (holds calcium)

NMJ and the Sarcomere Drawing

COLORCOLOR and and LABEL LABEL the followingthe following Motor Neuron and synapse = yellowMotor Neuron and synapse = yellow Acetylcholine = orangeAcetylcholine = orange Sarcolemma = blueSarcolemma = blue Sarcoplasmic reticulum = brownSarcoplasmic reticulum = brown Calcium = pinkCalcium = pink Z line = blackZ line = black Actin = PurpleActin = Purple Troponin and tropomyosin = greyTroponin and tropomyosin = grey Myosin = RedMyosin = Red

IMPORTANT: Make sure to label all bands and zonesIMPORTANT: Make sure to label all bands and zones

I band, A band, Z line, H zoneI band, A band, Z line, H zone

For the test you must be able to draw and label all the structures of the NMJ and the Sarcomere

Neuromuscular Junction- NMJNeuromuscular Junction- NMJ Site where Nerve (Neuron) and Muscle Fiber meet Site where Nerve (Neuron) and Muscle Fiber meet

more precisely where synapse of nerve connects with more precisely where synapse of nerve connects with sarcolemma of the muscle cell sarcolemma of the muscle cell

NMJ- nerve talks to muscles using chemicalsNMJ- nerve talks to muscles using chemicals motor neuron stores neurotransmitters (acetylcholine) in motor neuron stores neurotransmitters (acetylcholine) in

synaptic vesicles- “bubbles that carry chemicals” synaptic vesicles- “bubbles that carry chemicals”

[neurotransmitters = chemical messengers] “chem messaging”[neurotransmitters = chemical messengers] “chem messaging”

Magnified view

AA Motor Unit controls a bundle of fibersMotor Unit controls a bundle of fibers

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

A Closer look at -- Myosin

Thick filaments are composed of myosin Thick filaments are composed of myosin myosin resembles golf clubs twisted togethermyosin resembles golf clubs twisted together myosin hands (cross bridges) extend toward actinmyosin hands (cross bridges) extend toward actin

Held in place by M line proteins in center of sarcomere.Held in place by M line proteins in center of sarcomere.

A closer look at -- Actin

Actin has a protein strand wrapped around it that Actin has a protein strand wrapped around it that protects actins binding sites and blocks myosin from protects actins binding sites and blocks myosin from connecting with actin.connecting with actin.

The protective protein strand is made up of 2 The protective protein strand is made up of 2 proteins called Troponin and Tropomyosinproteins called Troponin and Tropomyosin

When calcium is released from the sarcoplasmic When calcium is released from the sarcoplasmic reticulum it binds to sites on reticulum it binds to sites on tropomyosintropomyosin and and troponintroponin causing the protective strand to shift causing the protective strand to shift which uncovers actin’s binding site which uncovers actin’s binding site

Myosin and Actin are now allowed to connect with Myosin and Actin are now allowed to connect with each other. Myosin reaches out his hand to Actin each other. Myosin reaches out his hand to Actin and she readily takes hold of his hand and the two and she readily takes hold of his hand and the two slide pass each other. slide pass each other.

Sliding Filament Mechanism Of Contraction Myosin cross bridgesMyosin cross bridges

pull on thin filamentspull on thin filaments Thin filaments slide Thin filaments slide

inwardinward Z Line come toward Z Line come toward

each othereach other Sarcomeres shorten.The Sarcomeres shorten.The

muscle fiber shortens. The muscle fiber shortens. The muscle shortensmuscle shortens

Notice :Thick & thin Notice :Thick & thin filaments do not change in filaments do not change in lengthlength

Actin and Myosin a Love StoryActin and Myosin a Love Story Actin and Myosin are in love with each other and Actin and Myosin are in love with each other and

desperately want to hold hands with each otherdesperately want to hold hands with each otherThe problem:The problem:Actins overprotective brothers (T and T) hate Myosin and Actins overprotective brothers (T and T) hate Myosin and

keep him far from their younger sister keep him far from their younger sister

Steps for a Muscle ContractionSteps for a Muscle Contraction 1.1. A nerve impulse travels down motor neuron A nerve impulse travels down motor neuron

releases acetylcholine ACh from its synaptic releases acetylcholine ACh from its synaptic vesicles into the synaptic gap vesicles into the synaptic gap

(Cupid sends his love arrows ACh into muscle)(Cupid sends his love arrows ACh into muscle)

Steps for a Muscle ContractionSteps for a Muscle Contraction

2.2. ACh triggers a muscle impulse which travels to ACh triggers a muscle impulse which travels to sarcoplasmic reticulum.sarcoplasmic reticulum.

{Ach- like cupids arrows- creates a wave of love {Ach- like cupids arrows- creates a wave of love from the skin to heart} from the skin to heart}

Steps for a Muscle ContractionSteps for a Muscle Contraction 3. After the muscle impulse has been generated, 3. After the muscle impulse has been generated,

acetylcholinestacetylcholinesteraseerase [ACherase] rapidly destroys Ach [ACherase] rapidly destroys Ach (AChErases erases acetylcholine)(AChErases erases acetylcholine){Cupid arrows get destroyed but things are already set in {Cupid arrows get destroyed but things are already set in

motion) motion)

4.4. The muscle impulse causes the sarcoplasmic The muscle impulse causes the sarcoplasmic reticulum to releases its reticulum to releases its stored calcium.stored calcium.

{Actin knows her brothers T & T love milk so she {Actin knows her brothers T & T love milk so she gets some milk from the refrigerator} gets some milk from the refrigerator}

5.5. Calcium binds with troponin and tropomyosin Calcium binds with troponin and tropomyosin molecules on actin, which move aside, exposing molecules on actin, which move aside, exposing the myosin the myosin binding sites on the actin binding sites on the actin filaments.filaments.

{{The T & T brothers drink the milk and forget about their The T & T brothers drink the milk and forget about their job of protecting the younger sister leaving her open to Myosin’s job of protecting the younger sister leaving her open to Myosin’s outstreched arms and hands} outstreched arms and hands}

6.6. Myosin cross-bridges (hands) now bind and pull Myosin cross-bridges (hands) now bind and pull on the actin filaments, the two filaments now slide on the actin filaments, the two filaments now slide past one another causing the sarcomeres to past one another causing the sarcomeres to shorten. (requires ATP)shorten. (requires ATP)

{Actin and Myosin get to hold hands and hug one another}{Actin and Myosin get to hold hands and hug one another}

7.7. Calcium returns to sarcoplasmic reticulum, this Calcium returns to sarcoplasmic reticulum, this causes troponin and tropomyosin to cover up and causes troponin and tropomyosin to cover up and protect the myosin binding sites on actin protect the myosin binding sites on actin

{T and T get full of milk and then break up the love affair and throw out {T and T get full of milk and then break up the love affair and throw out Myosin and protect Actin once again.}Myosin and protect Actin once again.}

8.8. Actin and Myosin are no longer able to bind to one Actin and Myosin are no longer able to bind to one another and the muscle relaxesanother and the muscle relaxes

{Actin and Myosin are no longer able to hold each other hands and must {Actin and Myosin are no longer able to hold each other hands and must once again wait for a love arrow from “Nerve Cupid” to start the once again wait for a love arrow from “Nerve Cupid” to start the whole thing over again}whole thing over again}

Relaxation Contraction

Rigor MortisRigor Mortis

Body becomes stiff after deathBody becomes stiff after death

"actin and myosin filaments of the muscle fibers "actin and myosin filaments of the muscle fibers remain linked because ATP is no longer produced remain linked because ATP is no longer produced

{Actin and Myosin hold hands forever}{Actin and Myosin hold hands forever}

Draw the NMJ and the Sarcomere label all structures

Draw the NMJ and the Sarcomere label all structures

Draw the NMJ and the Sarcomere label all structures

Stimulus for ContractionStimulus for Contraction 1.The motor neuron must release the neurotransmitter 1.The motor neuron must release the neurotransmitter

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

2.2. Protein receptors in the motor end plate detect the Protein receptors in the motor end plate detect the neurotransmitters, and a muscle impulse spreads over the neurotransmitters, and a muscle impulse spreads over the surface of the sarcolemma and into the Tsurface of the sarcolemma and into the T tubules, tubules, where it reaches the sarcoplasmic reticulum.where it reaches the sarcoplasmic reticulum.

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 stored calciumcalcium to the muscle fiber. to the muscle fiber.

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

5.5. Myosin cross-bridges (oars) now bind and pull Myosin cross-bridges (oars) now bind and pull on the on the actin filaments, causing the sarcomeres to shorten.actin filaments, causing the sarcomeres to shorten.

6.6. After the nervous impulse has been received, After the nervous impulse has been received, acetylcholinesterase rapidly decomposes the acetylcholine.acetylcholinesterase rapidly decomposes the acetylcholine.

7.7. Then, calcium is returned to the sarcoplasmic reticulum, Then, calcium is returned to the sarcoplasmic reticulum, and the and the linkages between myosin and actin are linkages between myosin and actin are broken. The muscle then relaxesbroken. The muscle then relaxes

Study Analogy: Study Analogy: Think of a love story. The Think of a love story. The actin and myosin are in love and would love to hold actin and myosin are in love and would love to hold hands. However, Actin is being guarded by hands. However, Actin is being guarded by Troponin and Tropomysin (Actin’s older Twin Troponin and Tropomysin (Actin’s older Twin brothers) Actin’s friend Neuron wants Actin and brothers) Actin’s friend Neuron wants Actin and Myosin to get together so she calls (call=nerve Myosin to get together so she calls (call=nerve impulse) for a pizza to be delivered to Actin’s house impulse) for a pizza to be delivered to Actin’s house to distract Troponin and Tropomysin.The to distract Troponin and Tropomysin.The pizzaman(acetylcholine) deliveres the pizza pizzaman(acetylcholine) deliveres the pizza (calcium) and the pizza distracts the T&T brothers (calcium) and the pizza distracts the T&T brothers and gives Myosin the chance to finally hold the hand and gives Myosin the chance to finally hold the hand of his beautifully thin lover Actin. of his beautifully thin lover Actin.

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

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 and chemical is in limited supply and so so must often be regeneratedmust often be regenerated2.2. Creatine phosphateCreatine phosphate, which stores , which stores excess energy released by the excess energy released by the mitochondria, is present to mitochondria, is present to regenerate ATP from ADP and regenerate ATP from ADP and phosphate.phosphate.

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 transferred to ADP molecules, to ADP molecules, converting them back to ATP. converting them back to ATP.

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

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.

3.3. Oxygen debt refers to the amount of Oxygen debt refers to the amount of oxygen that liver cells require oxygen that liver cells require

to convert to convert the accumulated lactic acid the accumulated lactic acid into glucose, into glucose, plus the amount that plus the amount that muscle cells need muscle cells need to resynthesize ATP to resynthesize ATP and creatine and creatine phosphate to their phosphate to their original original concentrations.concentrations.

4.4. Repaying oxygen debt may take Repaying oxygen debt may take several several hours. hours.

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

2.2. Muscle fatigue usually arises from the Muscle fatigue usually arises from 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 prevents accumulated 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 fibers can relax.muscle fibers can relax.

COOL informationCOOL information

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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 lost as heat

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

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

function is to remove a single fiber and function is to remove a single fiber and connect it to a device that records its connect it to a device that records its responses to electrical stimulation.responses to electrical stimulation.

B.B. Threshold StimulusThreshold Stimulus1.1. A muscle fiber remains A muscle fiber remains

unresponsive to stimulation unresponsive to stimulation unless the stimulus is of a certain unless the stimulus is of a 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 The time delay between when the stimulus is applied and when stimulus is applied and when

the muscle the muscle contracts is called the contracts is called the latent latent periodperiod, , which is less than 0.01 which is less than 0.01 second.second.

4.4. The latent period is followed by a The latent period is followed 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 frequency reaches stimuli of increasing frequency reaches a point when it is unable to relax a point when it is unable to relax completely and the force of individual completely and the force of individual twitches combine by the process of twitches combine 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 can produce a sustained

contraction of 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 state of sustained contraction of motor of 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 in The mechanism of contraction in cardiac muscle is essentially cardiac muscle is essentially

the same as the same as that for skeletal and smooth that for skeletal and smooth muscle, but muscle, but with some differences. with some differences.

B.B. Cardiac muscle has transverse Cardiac muscle has transverse tubules tubules that supply extra calcium, and that supply extra calcium, and can thus can thus contract for longer periods.contract for longer 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 muscle The immovable end of a muscle is the is the originorigin, while the movable , while the movable end is the insertion; contraction end is the insertion; contraction pulls the pulls the insertioninsertion toward the toward the origin.origin.

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

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. .

Major Skeletal MusclesMajor Skeletal Muscles

“I will pump you up girly man”

Muscles named according to: Muscles named according to:

SizeSize- Maximus versus minimus, longus and brevis- Maximus versus minimus, longus and brevis

ShapeShape- Deltoid = triangle, Trapezius = trapezoid- Deltoid = triangle, Trapezius = trapezoid

LocationLocation- Frontalis, zygomaticus, brachioradialis- Frontalis, zygomaticus, brachioradialis

Muscles named according to: Muscles named according to: ActionAction- Flexor digitorum, Pronator Teres - Flexor digitorum, Pronator Teres

Number attachments-Number attachments- Bicep, Tricep Bicep, Tricep

Direction of fibers-Direction of fibers- Rectus = straight , Oblique = angled Rectus = straight , Oblique = angled

Muscles of Facial ExpressionMuscles of Facial Expression

Muscle Location Action Muscle Location Action

Frontalis Frontalis forehead raises eye brow forehead raises eye brow

Orbicularis oculiOrbicularis oculi circle ms. around eye closes eyes circle ms. around eye closes eyes

ZygomaticusZygomaticus cheek to corner mouth smile cheek to corner mouth smile

Orbicularis orisOrbicularis oris circle ms. around mouth protrudes lips(kiss) circle ms. around mouth protrudes lips(kiss)

Platysma Platysma lower jaw and front neck opens mouth lower jaw and front neck opens mouth

Muscles for chewingMuscles for chewing

Muscle Location ActionMuscle Location Action MasseterMasseter back of cheek closes jaw back of cheek closes jaw TemporalisTemporalis over temporal bone closes over temporal bone closes jawjaw

MMuscles that Move the Headuscles that Move the Head

Muscle Location ActionMuscle Location Action

SternocleidomastoidSternocleidomastoid side of neck flex side of neck flex neckneck

Splenius capitisSplenius capitis back of neck ext. or rotat. back of neck ext. or rotat.bandage

8 - 108

Muscles of the Abdominal WallMuscles of the Abdominal Wall

This group of muscles connects the ribcage and vertebral column to the This group of muscles connects the ribcage and vertebral column to the pelvic girdle.pelvic girdle.

Muscle Location ActionMuscle Location ActionExternal obliqueExternal oblique side stomach like belt/girdle side stomach like belt/girdle

Rectus AbdominusRectus Abdominus front stomach flexes spine front stomach flexes spine “ “6-pack” 6-pack”

Muscles used in back extensionMuscles used in back extensionMuscle Location ActionMuscle Location Action

Quadratus LumborumQuadratus Lumborum Low back extends back Low back extends back

Erector Spinae Low back extends back Erector Spinae Low back extends back

Muscles used in breathingMuscles used in breathingMuscle Location ActionMuscle Location ActionDiaphragmDiaphragm inferior to lungs breathing inferior to lungs breathing

External IntercostalsExternal Intercostals between ribs breathing between ribs breathing

Muscles that Move the Shoulder Muscles that Move the Shoulder

Muscle Location ActionMuscle Location ActionTrapeziusTrapezius occiput to scapula to T12 shoulder shrug occiput to scapula to T12 shoulder shrug

Levator ScapulaLevator Scapula C1-C6 to scapula elevates scapula C1-C6 to scapula elevates scapula

Rhomboid MajorRhomboid Major T1-T6 to scapula raises/adducts scapula T1-T6 to scapula raises/adducts scapula

Muscles that Move the HumerusMuscles that Move the Humerus Muscle Location ActionMuscle Location ActionPectoralis MajorPectoralis Major Chest pulls arms forward Chest pulls arms forward Latissimus DorsiLatissimus Dorsi lower back to arm Adducts/extends arm lower back to arm Adducts/extends armDeltoid Deltoid top shoulder abducts arm top shoulder abducts arm SupraspinatusSupraspinatus top scapula abducts arm top scapula abducts arm

Infraspinatus Infraspinatus top of scapula rotates arm top of scapula rotates arm

Teres MajorTeres Major scapula extends arms scapula extends arms

Muscles that Move the ForearmMuscles that Move the Forearm

Muscle Location ActionMuscle Location Action Biceps Biceps ant. humerus (10) flex forearm ant. humerus (10) flex forearmBrachioradialis Brachioradialis ant. Inf. humerus (11) flex forearm ant. Inf. humerus (11) flex forearmBrachialis Brachialis lateral humerus (13) flex forearm lateral humerus (13) flex forearmTriceps Triceps posterior humerus extends forearm posterior humerus extends forearm

Latissimus = Wide or broad

Muscles that Move the ForearmMuscles that Move the Forearm

Muscle Location ActionMuscle Location Action Pronator TeresPronator Teres by elbow joint pronates forearm by elbow joint pronates forearm

SupinatorSupinator by elbow joint supinates forearm by elbow joint supinates forearm

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

Muscle Location ActionMuscle Location Action Flexor digitorumFlexor digitorum 4-arm to fingers flex fingers 4-arm to fingers flex fingers

Extensor digitorumExtensor digitorum post. 4-arm to fingers extends fingers post. 4-arm to fingers extends fingers

Muscles that Move the ThumbMuscles that Move the Thumb

Muscle Location ActionMuscle Location Action Abductor Pollicus LongusAbductor Pollicus Longus abducts thumb abducts thumb

Adductor PollicusAdductor Pollicus adducts thumb adducts thumb

Muscles that Move the Femur Muscles that Move the Femur

Muscle Location ActionMuscle Location ActionPsoas MajorPsoas Major Lumbar-femur raise femur Lumbar-femur raise femur

Muscles that move femurMuscles that move femur

Muscle Location ActionMuscle Location Actiongluteus maximusgluteus maximus sacrum-femur extends femur sacrum-femur extends femur

gluteus mediusgluteus medius ilium-femur abducts femur ilium-femur abducts femur

Muscles that Move the Ankle, Foot, and ToesMuscles that Move the Ankle, Foot, and Toes

Muscle Location ActionMuscle Location Action

Tibialis anteriorTibialis anterior tibia-tarsals dorsiflex foot tibia-tarsals dorsiflex foot

extensor digitorumextensor digitorum tibia-phalanges extends toes tibia-phalanges extends toes

Muscles that move footMuscles that move foot

Muscle Location ActionMuscle Location ActionGastrocnemius Gastrocnemius femur-calcaneus tippy toes femur-calcaneus tippy toes

SoleusSoleus tibia-calcaneus tippy toes tibia-calcaneus tippy toes

Muscles that move femurMuscles that move femur

Muscle Location ActionMuscle Location Actiongluteus mediusgluteus medius ilium-femur ilium-femur ababducts femur ducts femur

tensor fasciae lataetensor fasciae latae ilium-fascia thigh ilium-fascia thigh ababducts femurducts femur

Muscles that move the femurMuscles that move the femur

Muscle Location ActionMuscle Location ActionPiriformisPiriformis sacrum to femur sacrum to femur rotates rotates femur femur

adductor longusadductor longus pubic-femur adducts femur pubic-femur adducts femur

Muscles that Move lower leg- “Quadriceps” Muscles that Move lower leg- “Quadriceps”

Muscle Location ActionMuscle Location Action

Rectus FemorisRectus Femoris ilium-patella extends L.L. ilium-patella extends L.L.

Vastus IntermediusVastus Intermedius femur-patella extends L.L. femur-patella extends L.L.

Vastus LateralisVastus Lateralis femur-patella extends L.L. femur-patella extends L.L.

Vastus MedialisVastus Medialis femur-patella extends L.L. femur-patella extends L.L.

FILMFILM Vastus=GREAT Vastus=GREAT

Muscles that Move the lower legMuscles that Move the lower leg (Hamstrings) (Hamstrings)

Muscle Location ActionMuscle Location Action

biceps femorisbiceps femoris ishium-tibia flexes L.L ishium-tibia flexes L.L

Semitendinosus Semitendinosus ishium-tibia flexes L.L ishium-tibia flexes L.L

semimembranosussemimembranosus ishium-tibia flexes L.L ishium-tibia flexes L.L

Bi SemiBi Semi

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

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

1. Deltoid: scapula/clavicle to humerus- abducts arm2. Levator scapulae: C-vertebrae to scapula- elevates scapula3. Infraspinatus: lower scapular spine to humeral head- lateral rotation of humerus4. Teres major: scapula to anterior humerus- medial rotation of humerus'5. Teres Minor: scapula to posterior humerus- lateral rotaion of humerus6. Supraspinatus: upper scapular spine to humeral head- abducts humerus7. Trapezius- shoulder shrug8. Rhomboidius: T-vertebrae to scapula- raise/adduct scapula9. Latissimus Dorsi- adducts humerus10. Biceps: scapula to radius- flex elbow11. Tricep- extends forearm (radius)12. Pronator: Medial humerus to radius- medial rotation of forearm (pronation)13. Brachioradialis- flexes forearm14. Flexor Digitorum: medial humerus/ulna to phalanges- flex fingers15. 16. Extensor digitorum: lateral humerus to phalanges- extend fingers17. Extensor carpi radialis: lateral humerus to 2nd/3rd metacarpal- extend/adduct hand

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