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

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.

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Structure of a Skeletal MuscleStructure of a Skeletal Muscle

A.A. Each muscle is an organ, Each muscle is an organ, comprised of comprised of skeletal muscle skeletal muscle tissue, connective tissues, tissue, connective 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, surround surround and separate and separate each muscle.each muscle.

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

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3.3. Sometimes muscles are connected Sometimes muscles are connected to 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 The layer of connective tissue around around each whole muscle is the each whole muscle is the epimysium; ;

the the perimysium surrounds surrounds individual individual bundles (bundles (fascicles)fascicles) within each muscle; within each muscle; and each and each muscle cell (fiber) is covered muscle cell (fiber) is covered

by a connective tissue layer called by a connective tissue layer called endomysium.

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

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, is a single,

long, long, cylindrical muscle cylindrical muscle cell.cell.

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

sarcoplasmsarcoplasm (cytoplasm) with many(cytoplasm) with many

mitochondria and nuclei; the mitochondria and nuclei; the sarcoplasm contains sarcoplasm contains

myofibrils.

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a.a. Thick filaments of Thick filaments of myofibrils are myofibrils are made up of the made up of the protein 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 extends from Z line extends from Z line to Zto Z

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

of 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

HH zone, consisting of myosin zone, consisting of myosin

filaments only.filaments only.8 - 10

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

(endoplasmic reticulum), (endoplasmic reticulum), which is which is associated with associated with transverse (T) tubulestransverse (T) tubules

(invaginations of the (invaginations of the sarcolemma).sarcolemma).

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a.a. Each T tubule lies between Each T tubule lies between two 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 The sarcoplasmic reticulum and and transverse tubules activate transverse tubules activate the the muscle contraction muscle contraction mechanismmechanism

when the fiber is stimulated. when the fiber is stimulated.

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D.D. Neuromuscular Junction 1.1. The site where the motor neuron The site where the motor neuron

and and muscle fiber meet is the muscle fiber meet is the

neuromuscularneuromuscular junction.junction.a.a. The muscle fiber membrane The muscle fiber membrane

forms a forms a motor end platemotor end plate in which in which the sarcolemma is the sarcolemma is tightly folded tightly folded and where and where nuclei and nuclei and mitochondria mitochondria are abundant.are abundant.

b.b. The cytoplasm of the motor The cytoplasm of the motor neuron contains neuron contains

numerous numerous mitochondria and mitochondria and synapticsynaptic vesicles vesicles storing storing neurotransmitters.neurotransmitters.

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E.E. Motor Units

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

motor unit contract all motor unit contract all at once. at once.

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

several several components that components that result in the shorteningresult in the shortening

of sarcomeres,of sarcomeres, and the and the pulling of thepulling of the

muscle against its muscle against its attachments.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 globular cross-bridges projected outward with globular cross-bridges projected outward

alongalong

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 are two proteinsproteins

associated with the surface of the actin associated with the surface of the actin filaments.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 motor neuron must release

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

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

muscle impulse spreads over the muscle impulse spreads over the surface 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 Upon receipt of the muscle impulse, the impulse, the sarcoplasmic sarcoplasmic reticulum releases its reticulum releases its

stored calcium to the stored calcium to the sarcoplasm of the sarcoplasm of the muscle fiber.muscle fiber.

4.4. The high concentration of The high concentration of calcium incalcium in

the sarcoplasm interacts the sarcoplasm interacts with the with the troponin and troponin and tropomyosin molecules, tropomyosin molecules, which which move aside, exposing the myosin move aside, exposing the myosin

binding sites on the actin binding sites on the actin filaments.filaments.

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

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

been been received, received, acetylcholinesterase rapidly acetylcholinesterase rapidly

decomposes the acetylcholine.decomposes the acetylcholine.7.7. Then, calcium is returned to the Then, calcium is returned to the

sarcoplasmic reticulum, sarcoplasmic reticulum, and the and the

linkages between myosin and linkages between myosin and actin are actin are broken. broken.

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Study Analogy: Study Analogy: Think of a very familiar Think of a very familiar love story. The actin and myosin are in love love story. The actin and myosin are in love and would love to bind (keep it clean, think and would love to bind (keep it clean, think kiss). However, the actin is being guarded by kiss). However, the actin is being guarded by the troponin and tropomysin (T-T complex), the troponin and tropomysin (T-T complex), perhaps they are her parents or guardians? perhaps they are her parents or guardians? But someone is looking out for the love birds, But someone is looking out for the love birds, maybe a fairy godmother? They send a maybe a fairy godmother? They send a messenger in the form of a nerve impulse. messenger in the form of a nerve impulse. This messenger isn’t someone allowed in the This messenger isn’t someone allowed in the house, so they send a second messenger house, so they send a second messenger (acetylocholinesterase) by way of the trusty T-(acetylocholinesterase) by way of the trusty T-tubules. This messenger releases a distractor tubules. This messenger releases a distractor (aka calcium). Pretend this is a belly dancer (aka calcium). Pretend this is a belly dancer or someone from Publisher’s clearing house or 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 Contraction 1. 1. Energy for Energy for contraction comescontraction comes

from molecules of from molecules of ATPATP. This . This chemical is in limited supplychemical is in limited supplyand so must often be regeneratedand so must often be regenerated2.2. Creatine phosphateCreatine phosphate, which , which

stores stores excess energy excess energy released by the released by the

mitochondria, is present tomitochondria, is present to regenerate ATP from ADP and regenerate ATP from ADP and

phosphate.phosphate.

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

promotes the synthesis of creatine promotes the synthesis of creatine phosphate.phosphate.

4.4. As ATP decomposes, the energy As ATP decomposes, the energy

from creatine phosphate can be from creatine phosphate can be

transferred to ADP molecules, transferred to ADP molecules,

converting them back to ATP. converting them back to ATP.

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E.E. Oxygen Supply and Cellular Respiration

1.1. The early phase of cellular The early phase of cellular respirationrespiration

yields few molecules of ATP, so yields few molecules of ATP, so muscle muscle

has a high requirement for has a high requirement for oxygen, oxygen,

which enables the complete which enables the complete breakdown of glucose in thebreakdown of glucose in the

mitochondria.mitochondria.

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

3.3. The pigment myoglobin stores The pigment myoglobin stores oxygen oxygen in muscle tissue. in muscle tissue. 8 -

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F.F. Oxygen Debt1.1. During rest or moderate During rest or moderate

activity, there activity, there is enough oxygen is enough oxygen to support aerobic to support aerobic

respiration.respiration.2.2. Oxygen deficiency may Oxygen deficiency may

develop during develop during strenuous strenuous exercise, and lactic acid 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 diffuses out of muscle of muscle cells and is cells and is carried in the carried in the bloodstream to the liver.bloodstream to the liver.

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

convert the accumulated convert the accumulated lactic acid into lactic acid into glucose, glucose, PLUS PLUS the the amount that muscleamount that muscle

cells need to resynthesize cells need to resynthesize ATP and ATP and creatine creatine phosphate to their original phosphate to their original

concentrations.concentrations.

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

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

contract during strenuous exercise, contract during strenuous exercise, it is 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 accumulated lactic acid preventsprevents

the muscle from contracting.the muscle from contracting.

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

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H.H. Heat Production

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

important source of heat important 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 source of lost as heat (another source of heat for 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 function is to remove a single fiber and fiber and connect it to a device that connect it to a device that records its records its responses to electrical responses to electrical stimulation.stimulation.

B. B. Threshold Stimulus1. 1. A muscle fiber remainsA 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 strength, called the

thresholdthreshold stimulus. stimulus.

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C.C. All-or-None Response

1.1. When a muscle fiber When a muscle fiber contracts, it contracts, it

contracts to its full extent contracts to its full extent (all-or-none (all-or-none response); it response); it cannot contract partially. cannot 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 A single, short contraction involving involving

only a few motor units is referred only a few motor units is referred to as a to as a

twitch.twitch.

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

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 period of contraction and a period of and a period of

relaxation. relaxation.

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E.E. Summation Summation

1.1. A muscle fiber receiving a series A muscle fiber receiving a series of 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 the force of completely and the force of individual individual twitches combine by twitches combine by the process of the process of

summationsummation..

2.2. If the sustained contraction lacks If the sustained contraction lacks any 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 motor units within a muscle at highermuscle at higher

intensities of stimulation is intensities of stimulation is called 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 can produce a sustained contraction

of of

increasing strength.increasing strength.

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

units within a muscle. units within a muscle.

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Smooth MusclesSmooth Muscles

A.A. Smooth Muscle Fibers

1.1. Smooth muscle cells are Smooth muscle cells are elongated with tapered ends, lack elongated with tapered ends, lack striations, and have a relatively striations, and have a relatively undeveloped sarcoplasmic undeveloped sarcoplasmic reticulum.reticulum.

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

types of types of smooth muscles.smooth muscles.

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

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b.b. Visceral smooth muscle Visceral smooth muscle occurs in occurs in sheets and is sheets and is found in the walls of found in the walls of hollow organs; these fibers can hollow organs; these fibers can

stimulate one another stimulate one another and display and display rhythmicity, rhythmicity, and are thus 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-The myosin-binding-to-

actin actin mechanism is the mostly same mechanism is the mostly same for 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 Hormones can also stimulate or inhibit or inhibit contraction.contraction.

4.4. Smooth muscle is slower to Smooth muscle is slower to contract contract and relax than is and relax than is skeletal muscle, but skeletal muscle, but can can contract longer using the same contract longer using the same

amount of ATP. amount of ATP.

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Cardiac Muscle

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

B.B. Cardiac muscle has Cardiac muscle has transverse transverse tubules that tubules that supply extra calcium, supply extra calcium, and can and can thus contract for longer thus contract for longer periods.periods.

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

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

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

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Skeletal 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 one insertion or origin.origin.

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B.B. Interaction 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 prime movermover..

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 Muscles

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

and are responsible for and are responsible for the variety of facial the variety of facial expressions expressions possible in the human possible in the human face.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 Chewing movements

include up include up and down as well as and down as well as side-to-side side-to-side grinding motions of grinding motions of muscles 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 Muscles that Move the Pectoral GirdleGirdle

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 rhomboideus major,levator scapulae,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 coracobrachialis and pectoralis

major.major.

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3.3. Extensors Extensors include the teres include the teres major 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 connect to the ulna and radius.to the ulna and radius.

2.2. Flexors are the biceps Flexors are the biceps brachii,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 Rotators include the supinator, supinator,

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

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H.H. Muscles that Move the Wrist, Hand, and Muscles that Move the Wrist, Hand, and FingersFingers1.1. Movements of the hand are Movements of the hand are

caused by caused by muscles muscles originating from the distal 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 palmaris longus, and flexor

digitorum digitorum profundus.profundus.

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3.3. Extensors include the Extensors include the extensor carpiextensor carpi

radialis longus, extensor radialis longus, extensor carpi radialiscarpi 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 This group of muscles connects the

rib rib cage and vertebral column to the cage and vertebral column to the pelvic pelvic girdle.girdle.

a.a. A band of tough connective A band of tough connective tissue, the linea alba, tissue, the linea alba,

extending extending from the from the xiphoid process to 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 external oblique, internal oblique, oblique, transverse transverse abdominis, and rectus abdominis, and 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 fills the space within the pubic arch, and within the pubic arch, and the the deeper pelvic diaphragm forms the deeper pelvic diaphragm forms the floor of the pelvic cavity.floor of the pelvic cavity.

2.2. Pelvic diaphragm ncludes the Pelvic diaphragm ncludes the

levator ani.levator ani.

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3.3. Urogenital diaphragm: Urogenital diaphragm: includes theincludes the

superficial transversus, superficial transversus, perinei,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 The muscles that move the thigh are thigh are attached to the attached to the femur and to the pelvic femur and to 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 gluteus minimus, and tensor fasciae tensor 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 medialis, and vastus

intermedius.intermedius.

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M.M.Muscles that Move the Ankle, Foot, and Muscles that Move the Ankle, Foot, and ToesToes1.1. Muscles that move the foot are Muscles that move the foot are

attached to the femur, fibula, attached to the femur, fibula, or or tibia, and move the foot tibia, and move the foot upward, upward, downward, or in a turning downward, or in a turning

motion.motion.2.2. Dorsal flexors include the tibialisDorsal flexors include the tibialis

anterior, 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 An invertor is the tibialis posterior.posterior.

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

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

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