163 ch 07_lecture_presentation

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PowerPoint® Lecture Slidesprepared byMeg FlemmingAustin Community College

C H A P T E R

TheMuscular System

7


Chapter 7 Learning Outcomes

• 7-1

• Specify the functions of skeletal muscle tissue.

• 7-2

• Describe the organization of muscle at the tissue level.

• 7-3

• Identify the structural components of a sarcomere.

• 7-4

• Explain the key steps involved in the contraction of a skeletal muscle fiber beginning at the neuromuscular junction.

• 7-5

• Compare the different types of muscle contractions.



• 7-6

• Describe the mechanisms by which muscles obtain the energy to power contractions.

• 7-7

• Relate the types of muscle fibers to muscle performance, and distinguish between aerobic and anaerobic endurance.

• 7-8

• Contrast the structures and functions of skeletal, cardiac, and smooth muscle tissues.

• 7-9

• Explain how the name of a muscle can help identify its location, appearance, or function.



• 7-10

• Identify the main axial muscles of the body together with their origins, insertions, and actions.

• 7-11

• Identify the main appendicular muscles of the body together with their origins, insertions, and actions.

• 7-12

• Describe the effects of aging on muscle tissue.

• 7-13

• Discuss the functional relationships between the muscular system and other organ systems.


Five Skeletal Muscle Functions (7-1)

1. Produce movement of the skeleton • By pulling on tendons that then move bones

2. Maintain posture and body position

3. Support soft tissues • With the muscles of the abdominal wall and the pelvic floor

4. Guard entrances and exits • In the form of sphincters

5. Maintain body temperature • When contraction occurs, energy is used and converted to

heat


Checkpoint (7-1)

1. Identify the five primary functions of skeletal

muscle.


Organization of Skeletal Muscle Tissue (7-2)

• Skeletal muscles

• Are organs that contain:

• Connective tissue

• Blood vessels

• Nerves

• Skeletal muscle tissue

• Single skeletal muscle cells

• Also called skeletal muscle fibers


Three Layers of Connective Tissue (7-2)

1. Epimysium

• Covers the entire muscle

2. Perimysium

• Divides the muscle into bundles called fascicles

• Blood vessels and nerves are contained in the

perimysium

3. Endomysium

• Covers each muscle fiber and ties fibers together

• Contains capillaries and nerve tissue


Tendons (7-2)

• Where the ends of all three layers of connective

tissue come together

• And attach the muscle to a bone

• Aponeurosis

• A broad sheet of collagen fibers that connects muscles to

each other

• Similar to tendons, but do not connect to a bone


Blood Vessels and Nerves (7-2)

• Extensive network of blood vessels in skeletal

muscle

• Provides high amounts of nutrients and oxygen

• To skeletal muscles which have high metabolic needs


Control of Skeletal Muscle (7-2)

• Mostly under voluntary control

• Must be stimulated by the central nervous system

• Axons

• Push through the epimysium

• Branch through the perimysium

• And enter the endomysium

• To control individual muscle fibers


Figure 7-1 The Organization of Skeletal Muscles.

Skeletal Muscle (organ)Epimysium Perimysium Endomysium Nerve

Musclefascicle

Musclefibers

Bloodvessels

Muscle Fascicle (bundle of fibers)

Perimysium

Muscle fiber

Endomysium

Epimysium

Blood vesselsand nerves

Endomysium

Perimysium

Tendon

Muscle Fiber (cell)Capillary Myofibril Endomysium

Sarcoplasm

MitochondrionStem cell

SarcolemmaNucleus

Axon of neuron


Checkpoint (7-2)

2. Describe the connective tissue layers associated

with a skeletal muscle.

3. How would severing the tendon attached to a

muscle affect the muscle's ability to move a body

part?


Features of Skeletal Muscle Fibers (7-3)

• Are specifically organized to produce contraction

and have specific names for general cell

structures

• Can be very long and are multinucleated

• Composed of highly organized structures, giving

them a striped or striated appearance


The Sarcolemma and Transverse Tubules (7-3)

• The sarcolemma

• Specific name of muscle fiber plasma membrane

• Has openings across the surface that lead into a network of

transverse tubules, or T tubules

• T tubules allow for electrical stimuli to reach deep into each

fiber

• The sarcoplasm

• Specific name for muscle fiber cytoplasm


Myofibrils in Muscle Fiber (7-3)

• Hundreds to thousands in each fiber

• Are encircled by T tubules and are as long as the

entire muscle fiber

• Are bundles of thick and thin myofilaments

• Actin molecules are found in thin filaments

• Myosin molecules are found in thick filaments

• Are the contractile proteins that shorten and are

responsible for contraction


The Sarcoplasmic Reticulum (7-3)

• Or SR

• Specialized smooth endoplasmic reticulum

• Expanded end that is next to the T tubule is the

terminal cisternae

• Contain high concentrations of calcium ions

• Triad

• A combination of two terminal cisternae and one T tubule


Sarcomeres (7-3)

• Smallest functional unit of skeletal muscle fiber

• Formed by repeating myofilament arrangements

• Each myofibril has about 10,000 sarcomeres

• Thick and thin filament arrangements are what

produce the striated appearance of the fiber

• Overlapping filaments define lines and bands


Sarcomere Lines (7-3)

• Z lines

• Thin filaments at both ends of the sarcomere

• Another protein connects the Z lines to the thick filament to

maintain alignment

• M line

• Made of connections between the thick filaments


Sarcomere Bands (7-3)

• A band

• Contains the thick filaments

• I band

• Contains the thin filaments, including the Z line


Figure 7-2 The Organization of a Skeletal Muscle Fiber.

T tubules Terminalcisterna

Sarcoplasmicreticulum Triad Sarcolemma

Mitochondria

Thickfilament

MyofilamentsThin filament

MYOFIBRIL

The structure of a skeletalmuscle fiber.

SARCOMERE

Z line Zone of overlap

M line

Myofibril

I band H band

A band Zone of overlap

The organization of a sarcomere, part of a single myofibril.

Z line M line Z line

A stretched outsarcomere.

Z line and thinfilaments

Active site

Z line

Actin molecules Thick filaments

M line

ACTINSTRAND

Troponin TropomyosinThin filament

MYOSIN MOLECULE

Myosin tail

Myosinhead

Hinge

The structure of a thick filament.

The structure of a thin filament.


Figure 7-2a The Organization of a Skeletal Muscle Fiber.

T tubules Terminalcisterna

Sarcoplasmicreticulum Triad Sarcolemma

Mitochondria

Thickfilament

MyofilamentsThin filament

MYOFIBRIL

The structure of a skeletalmuscle fiber.


Figure 7-2b The Organization of a Skeletal Muscle Fiber.

Z line Zone of overlapM line

Myofibril

I band H band Zone of overlapA band

SARCOMERE

The organization of a sarcomere, part of a single myofibril.


Figure 7-2c The Organization of a Skeletal Muscle Fiber.

Z line M line Z line

A stretched outsarcomere.

Z line and thinfilaments

Z line

Thick filaments

M line


Figure 7-2d The Organization of a Skeletal Muscle Fiber.

Active site Actin molecules

ACTINSTRAND

Troponin Tropomyosin

Thin filament

The structure of a thin filament.


Figure 7-2e The Organization of a Skeletal Muscle Fiber.

MYOSIN MOLECULE

Myosin tail

Myosinhead

Hinge

The structure of a thick filament.


Thin and Thick Filaments (7-3)

• Actin

• A thin twisted protein, with specific active sites for myosin to

bind to

• At rest, active sites are covered by strands of tropomyosin,

held in position by troponin

• Myosin

• A thick filament with tail and globular head that attaches to

actin active sites during contraction


Steps of Contraction (7-3)

1. Calcium released from SR

2. Calcium binds to troponin

3. Change of troponin shape causes tropomyosin to

move away from active sites

4. Myosin heads bind to active site, creating cross-

bridges, rotate and cause actin to slide over

myosin


Sliding Filament Theory (7-3)

• Based on observed changes in sarcomere

• I bands get smaller

• Z lines move closer together

• H bands decrease

• A bands don't change, indicating that the thin filaments are

sliding toward the center


Figure 7-3 Changes in the Appearance of a Sarcomere during Contraction of a Skeletal Muscle Fiber.

I band A band

Z line H band Z lineA relaxed sarcomere showinglocations of the A band, Z lines,and I band.

I band

During a contraction, the A band stays thesame width, but the Z lines move closertogether and the I band gets smaller.

Z line H band Z line

A band


Checkpoint (7-3)

4. Describe the basic structure of a sarcomere.

5. Why do skeletal muscle fibers appear striated

when viewed through a light microscope?

6. Where would you expect the greatest

concentration of calcium ions to be in a resting

skeletal muscle fiber?


The Neuromuscular Junction (7-4)

• Where a motor neuron communicates with a

skeletal muscle fiber

• Axon terminal of the neuron

• An enlarged end that contains vesicles of the

neurotransmitter

• Acetylcholine (ACh)

• The neurotransmitter that will cross the synaptic cleft


The Neuromuscular Junction (7-4)

• ACh binds to the receptor on the motor end plate

• Cleft and the motor end plate contain

acetylcholinesterase (AChE)

• Which breaks down ACh

• Neurons stimulate sarcolemma by generating an

action potential

• An electrical impulse


The cytoplasm of the axonterminal contains vesiclesfilled with molecules of ace-tylcholine, or ACh. Acetylcho-line is a neurotransmitter, achemical released by aneuron to change the perme-ability or other properties ofanother cell’s plasma mem-brane. The synaptic cleft andthe motor end plate containmolecules of the enzymeacetylcholinesterase (AChE),which breaks down ACh.

Vesicles ACh

Synaptic cleft

Motorend plate

AChE

Slide 1Figure 7-4 Skeletal Muscle Innervation.


The stimulus for AChrelease is the arrival of anelectrical impulse, oraction potential, at theaxon terminal. The actionpotential arrives at theNMJ after traveling alongthe length of the axon.

Arriving actionpotential



When the actionpotential reaches theneuron’s axon terminal,permeability changes inthe membrane trigger theexocytosis of ACh into thesynaptic cleft. Exocytosisoccurs as vesicles fusewith the neuron’s plasmamembrane.

Motor end plate



ACh molecules diffuseacross the synaptic cleftand bind to ACh receptorson the surface of the motorend plate. ACh bindingalters the membrane’spermeability to sodiumions. Because the extracell-ular fluid contains a highconcentration of sodiumions, and sodium ionconcentration inside the cellis very low, sodium ionsrush into the sarcoplasm.

ACh receptor site



The sudden inrush ofsodium ions results inthe generationof an action potentialin the sarcolemma.AChE quickly breaksdown the ACh on themotor end plate and inthe synaptic cleft, thusinactivating the AChreceptor sites.

Actionpotential

AChE



The Contraction Cycle (7-4)

• Involves the triads

• Action potential travels over the sarcolemma,

down into the T tubules

• Causes release of calcium from the SR

• Calcium binds to troponin and the contraction

cycle starts


Contraction CycleBegins

Myosin head

Troponin

ActinTropomyosin

Figure 7-5 The Contraction Cycle Slide 1


Active-Site Exposure

Sarcoplasm

Activesite



Cross-Bridge Formation



Myosin Head Pivoting



Cross-BridgeDetachment



Myosin Reactivation



Table 7-1 Steps Involved in Skeletal Muscle Contraction and Relaxation


Checkpoint (7-4)

7. Describe the neuromuscular junction.

8. How would a drug that blocks acetylcholine

release affect muscle contraction?

9. What would you expect to happen to a resting

skeletal muscle if the sarcolemma suddenly

became very permeable to calcium ions?


Contraction Produces Tension (7-5)

• As sarcomeres contract, so does the entire muscle

fiber

• As fibers contract, tension is created by tendons

pulling on bones

• Movement will occur only if the tension is greater

than the resistance

• Compression is a force that pushes objects

• Muscle cells create only tension, not compression



• Individual fibers

• Are either contracted or relaxed

• "On" or "off"

• Tension is a product of the number of cross-bridges a fiber

contains

• Variation in tension can occur based on:

• The amount of overlap of the myofilaments

• The frequency of stimulation

• The more frequent the stimulus, the more Ca2+ builds up,

resulting in greater contractions



• Whole skeletal muscle organ

• Contracts with varying tensions based on:

• Frequency of muscle fiber stimulation

• Number of fibers activated


A Muscle Twitch (7-5)

• A single stimulus-contraction-relaxation cycle in a

muscle fiber or whole muscle

• Represented by a myogram


Three Phases of a Muscle Twitch (7-5)

1. Latent period

• Starts at the point of stimulus and includes the action potential,

release of Ca2+, and the activation of troponin/tropomyosin

2. Contraction phase

• Is the development of tension because of the cross-bridge

cycle

3. Relaxation phase

• Occurs when tension decreases due to the re-storage of Ca2+

and covering of actin active sites


Figure 7-6 The Twitch and Development of Tension.

Maximum tensiondevelopment

Ten

sio

n

Stimulus

Time (msec) 0 5 10 20 30 40

Restingphase

Latentperiod

Contractionphase

Relaxationphase


Summation and Tetanus (7-5)

• Summation

• Occurs with repeated, frequent stimuli that trigger a response

before full relaxation has occurred

• Incomplete tetanus

• Near peak tension with little relaxation

• Complete tetanus

• Stimuli are so frequent that relaxation does not occur

ANIMATION Frog Wave SummationPLAYPLAY


Figure 7-7 Effects of Repeated Stimulations.

= Stimulus Maximum tension(in tetanus)

Time Time TimeSummation. Summationof twitches occurs whensuccessive stimuli arrivebefore the relaxation phasehas been completed.

Incomplete tetanus.Incomplete tetanus occursif the stimulus frequencyincreases further. Tensionproduction rises to a peak,and the periods ofrelaxation are very brief.

Complete tetanus.During complete tetanus,the stimulus frequency isso high that the relaxationphase is eliminated;tension plateaus atmaximal levels.

Ten

sio

n


Varying Numbers of Fibers Activated (7-5)

• Allows for smooth contraction and a lot of control

• Most motor neurons control a number of fibers

through multiple, branching axon terminals


Motor Unit (7-5)

• A single motor neuron and all the muscle fibers it

innervates

• Motor units are dispersed throughout the muscle

• Fine control movements

• Use motor units with very few fibers per neuron

• Gross movements

• Motor units have a high fiber-to-neuron ratio


Recruitment (7-5)

• A mechanism for increasing tension to create

more movement

• A graded addition of more and more motor units to

produce adequate tension


Figure 7-8 Motor Units.

Axons ofmotor neurons

SPINAL CORDMotornerve

Muscle fibersMotor unit 1

Motor unit 2

Motor unit 3

KEY


Muscle Tone and Atrophy (7-5)

• Muscle tone

• Some muscles at rest will still have a little tension

• Primary function is stabilization of joints and posture

• Atrophy

• Occurs in a muscle that is not regularly stimulated

• Muscle becomes small and weak

• Can be observed after a cast comes off a fracture


Types of Contraction (7-5)

• Isotonic contraction

• When the length of the muscle changes, but the tension

remains the same until relaxation

• For example, lifting a book

• Isometric contraction

• When the whole muscle length stays the same, the tension

produced does not exceed the load

• For example, pushing against a wall


Elongation of Muscle after Contraction (7-5)

• No active mechanism for returning a muscle to a

pre-contracted, elongated state

• Passively uses a combination of:

• Gravity

• Elastic forces

• Opposing muscle movement


Checkpoint (7-5)

10. What factors are responsible for the amount of

tension a skeletal muscle develops?

11. A motor unit from a skeletal muscle contains

1500 muscle fibers. Would this muscle be

involved in fine, delicate movements or in

powerful, gross movements? Explain.

12. Can a skeletal muscle contract without

shortening? Explain.


ATP and CP Reserves (7-6)

• At rest, muscle cells generate ATP, some of which

will be held in reserve

• Some is used to transfer high energy to creatine

forming creatine phosphate (CP)


ATP and CP Reserves (7-6)

• During contraction each cross-bridge breaks down ATP into ADP and a phosphate group • CP is then used to recharge ATP

• The enzyme creatine phosphokinase (CPK or CK) regulates this reaction • It lasts for about 15 seconds

• ATP must then be generated in a different way


Aerobic Metabolism (7-6)

• Occurs in the mitochondria

• Using ADP, oxygen, phosphate ions, and organic substrates

from carbohydrates, lipids, or proteins

• Substrates go through the citric acid cycle

• A series of chemical reactions that result in energy to make

ATP, water, and carbon dioxide

• Oxygen supply decides ATP aerobic production


Glycolysis (7-6)

• Breaks glucose down to pyruvate in the cytoplasm

of the cell

• If pyruvate can go through the citric acid cycle with

oxygen, it is very efficient

• Forming about 34 ATP

• With insufficient oxygen, pyruvate yields only 2

ATP

• Pyruvate is converted to lactic acid

• Potentially causing a pH problem in cells


Figure 7-9 Muscle Metabolism.Fatty acids G Blood vessels

Glucose Glycogen

MitochondriaCreatine

Resting: Fatty acids are catabolized; the ATP producedis used to build energy reserves of ATP, CP, and glycogen.

Fatty acids

Glucose Glycogen

Pyruvate

2

2

34

34

To myofibrils to supportmuscle contraction

Moderate activity: Glucose and fatty acids are catabolized;the ATP produced is used to power contraction.

Lactate

Glucose Glycogen

PyruvateCreatine

2

2


Peak activity: Most ATP is produced through glycolysis,with lactate and hydrogen ions as by-products. Mitochondrial activity (not shown) now provides only about one-third of the ATP consumed.

Lactate


Figure 7-9a Muscle Metabolism.

Fatty acids Blood vessels

Glucose

G

Glycogen

MitochondriaCreatine

Resting: Fatty acids are catabolized; the ATP producedis used to build energy reserves of ATP, CP, and glycogen.


Figure 7-9b Muscle Metabolism.

Fatty acids

Glucose Glycogen

Pyruvate

2

34


34

2

Moderate activity: Glucose and fatty acids are catabolized;the ATP produced is used to power contraction.


Peak activity: Most ATP is produced through glycolysis,with lactate and hydrogen ions as by-products. Mitochondrialactivity (not shown) now provides only about one-third of the ATP consumed.

Lactate

Glucose Glycogen

Pyruvate

Lactate

Creatine


2

2

Figure 7-9c Muscle Metabolism.


Muscle Fatigue (7-6)

• Caused by depletion of energy reserves or a

lowering of pH

• Muscle will no longer contract even if stimulated

• Endurance athletes, using aerobic metabolism,

can draw on stored glycogen and lipids

• Sprinters, functioning anaerobically, deplete CP

and ATP rapidly, and build up lactic acid

ANIMATION Frog FatiguePLAYPLAY


The Recovery Period (7-6)

• Requires "repaying" the oxygen debt by continuing to

breathe faster

• Even after the end of exercise, and recycling lactic acid

• Heat production occurs during exercise

• Raising the body temperature

• Blood vessels in skin will dilate; sweat covers the skin and

evaporates

• Promoting heat loss


Checkpoint (7-6)

13. How do muscle cells continuously synthesize

ATP?

14. What is muscle fatigue?

15. Define oxygen debt.


Muscle Performance (7-7)

• Measured in force

• The maximum amount of tension produced by a muscle or

muscle group

• Measured in endurance

• The amount of time a particular activity can be performed

• Two keys to performance

1. Types of fibers in muscle

2. Physical conditioning or training


Fast Fibers (7-7)

• The majority of muscle fibers in the body

• Large in diameter

• Large glycogen reserves

• Few mitochondria

• Rely on glycolysis

• Are rapidly fatigued


Slow Fibers (7-7)

• About half the diameter of, and three times slower

than, fast fibers

• Are fatigue resistant because of three factors

1. Oxygen supply is greater due to more perfusion

2. Myoglobin stores oxygen in the fibers

3. Oxygen use is efficient due to large numbers of mitochondria


Percentages of Muscle Types Vary (7-7)

• Fast fibers appear pale and are called white

muscles

• Extensive vasculature and myoglobin in slow

fibers cause them to appear reddish and are

called red muscles

• Human muscles are a mixture of fiber types and

appear pink


Muscle Conditioning and Performance (7-7)

• Physical conditioning and training

• Can increase power and endurance

• Anaerobic endurance

• Is increased by brief, intense workouts

• Hypertrophy of muscles results

• Aerobic endurance

• Is increased by sustained, low levels of activity


Checkpoint (7-7)

16. Why would a sprinter experience muscle fatigue

before a marathon runner would?

17. Which activity would be more likely to create an

oxygen debt in an individual who regularly

exercises: swimming laps or lifting weights?

18. Which type of muscle fibers would you expect

to predominate in the large leg muscles of

someone who excels at endurance activities

such as cycling or long-distance running?


Cardiac Muscle Tissue (7-8)

• Found only in heart

• Cardiac muscle cells

• Relatively small with usually only one central nucleus

• Striated and branched

• Intercalated discs, which connect cells to other cells

• Communicate through gap junctions, allowing all the fibers to

work together


Cardiac Pacemaker Cells (7-8)

• Exhibit automaticity

• Make up only 1 percent of myocardium

• Establish rate of contraction


Cardiac Contractile Cells (7-8)

• 99 percent of myocardium

• Contract for longer period than skeletal muscle

fibers

• Unique sarcolemmas make tetanus impossible

• Are permeable to calcium

• Rely on aerobic metabolism


Smooth Muscle Tissue (7-8)

• Found in the walls of most organs, in the form of

sheets, bundles, or sheaths

• Lacks myofibrils, sarcomeres, or striations

• Smooth muscle cells

• Also smaller than skeletal fibers

• Spindle-shaped and have a single nucleus



• Thick filaments are scattered throughout

sarcoplasm

• Thin filaments are anchored to the sarcolemma

• Causing contraction to be like a twisting corkscrew

• Cells are bound together

• Resulting in forces being transmitted throughout the tissue



• Different from other muscle types

• Calcium ions from the extracellular fluid are needed to trigger

a contraction mechanism that is different from other muscle

tissues

• Function involuntarily

• Can respond to hormones or pacesetter cells


Figure 7-10 Cardiac and Smooth Muscle Tissues.

A light micrograph of cardiac muscle tissue.

Intercalateddiscs

Cardiacmuscle cell

Circularmuscle layer

Longitudinalmuscle layer

Many visceral organs contain several layers of smoothmuscle tissue oriented in different directions. Here, asingle sectional view shows smooth muscle cells inboth longitudinal (L) and transverse (T) sections.

Cardiac muscle tissue

Smooth muscle tissue

LM x 575

LM x 100

L

T


Table 7-2 A Comparison of Skeletal, Cardiac, and Smooth Muscle Tissues


Checkpoint (7-8)

19. How do intercalated discs enhance the

functioning of cardiac muscle tissue?

20. Extracellular calcium ions are important for the

contraction of what type(s) of muscle tissue?

21. Why can smooth muscle contract over a wider

range of resting lengths than skeletal muscle?


Skeletal Muscle System Names (7-9)

• Based on:

• Action

• What they do

• Origin

• The end that stays stationary

• Insertion

• The end that moves


Actions (7-9)

• Described as relative to the bone that is moved

• Example, "flexion of the forearm"

• Described as the joint that is involved

• Example, "flexion at the elbow"


Primary Actions of Muscles (7-9)

• Prime mover, or agonist

• The muscle that is chiefly responsible for producing a movement

• Antagonist

• A muscle that opposes another muscle

• Synergist

• A muscle that helps the prime mover

• Example, flexion of the elbow

• The biceps brachii is the prime mover, the triceps brachii is the antagonist, and the brachialis is the synergist


Table 7-3 Muscle Terminology (1 of 2)


Table 7-3 Muscle Terminology (2 of 2)


Muscle Terminology (7-9)

• Combining the various terms in Table 7-3,

anatomists name the muscles using:

• Location, direction of fibers, number of origins, and/or

function

• Muscles are organized into two groups

1. Axial muscles (mostly stabilizers)

2. Appendicular muscles (stabilizers or movers of the limbs)


Figure 7-11a An Overview of the Major Skeletal Muscles.

Frontalis

Temporalis

Masseter

Sternocleidomastoid

TrapeziusClavicle

Deltoid

Pectoralis major

Biceps brachiiTriceps brachii

BrachialisPronator teres

Palmaris longusFlexor carpi radialis

Flexor digitorumTensor fasciae

latae

Vastus lateralisRectus femoris

PatellaTibia

Tibialis anteriorExtensor digitorum

SternumLatissimus dorsi Serratus anterior External oblique Rectus abdominis

Extensor carpi radialisBrachioradialisFlexor carpi ulnaris

GluteusmediusIliopsoas

Adductor longus GracilisSartoriusVastus medialis

FibularisGastrocnemiusSoleus

Anterior view


Figure 7-11b An Overview of the Major Skeletal Muscles.

Sternocleidomastoid

TrapeziusDeltoid

InfraspinatusTeres minor

Latissimus dorsiBrachioradialisExtensor carpi

radialis

Occipitalis

Triceps brachii Rhomboid major

Flexor carpi ulnaris

External obliqueExtensor digitorum

Extensor carpi ulnarisGluteus medius

Gluteus maximusAdductor magnus SemimembranosusGracilisSartorius

Tensor fasciaelatae

SemitendinosusBiceps femoris

Gastrocnemius

Soleus

Calcanealtendon

Calcaneus

Teres major

Posterior view


Checkpoint (7-9)

22. Identify the kinds of descriptive information used

to name skeletal muscles.

23. Which muscle is the antagonist of the biceps

brachii?

24. What does the name flexor carpi radialis longus

tell you about this muscle?


Axial Muscles (7-10)

• Muscles of the head and neck

• Muscles of the spine

• Muscles of the trunk

• Muscles of the pelvic floor


Muscles of the Head and Neck (7-10)

• Orbicularis oris • Constricts the mouth opening

• Buccinator • Compresses check to blow forcefully

• Masseter • Prime mover for chewing

• Temporalis and pterygoid • Synergists for chewing

• Digastric • Depresses the mandible

• Sternocleidomastoid • Rotates head or flexes neck


Muscles of the Head and Neck (7-10)

• Epicranium, or scalp, contains a two-part muscle, the occipitofrontalis

1. Anterior frontalis

2. Posterior occipitalis

• Connected by epicranial aponeurosis

• Platysma

• Covers ventral neck extending from the base of the neck to the mandible

• Mylohyoid

• Supports the tongue

• Stylohyoid

1. Connects hyoid to styloid process


Figure 7-12 Muscles of the Head and Neck.

Epicranialaponeurosis

(tendinous sheet)Frontalis

Orbicularisoculi

ZygomaticusOrbicularis oris

Depressoranguli oris

Temporalis

Occipitalis

BuccinatorMasseterSternocleidomastoid

Lateral pterygoidMedial pterygoid

Mandible

Platysma

Zygomaticus

Orbicularis oris

Platysma

Sternocleidomastoid

Platysma(cut and reflected)

Epicranialaponeurosis(tendinous sheet)

FrontalisTemporalis

Orbicularisoculi

MasseterBuccinator

Depressoranguli oris

Trapezius

Lateral view

Lateral view, pterygoidmuscles exposed Anterior view


Figure 7-13 Muscles of the Anterior Neck.

Mylohyoid

Stylohyoid

Hyoid bone

Cartilagesof larynx

Sternothyroid

Sternohyoid

SternocleidomastoidCut heads of

sternocleidomastoid

Clavicle

Sternocleidomastoid(cut)

Digastric

MylohyoidMandible

Sternum


Table 7-4 Muscles of the Head and Neck (1 of 2)


Table 7-4 Muscles of the Head and Neck (2 of 2)


Muscles of the Spine (7-10)

• Splenius capitis and semispinalis capitis

• Work together to either extend the head or tilt the head

• Erector spinae

• Are spinal extensors and include spinalis, longissimus, and

iliocostalis

• Quadratus lumborum

• Flex the spinal column and depress the ribs


Figure 7-14 Muscles of the Spine.

Semispinalis capitis

Splenius capitis

Iliocostalis

Erectorspinaemuscles

Longissimus

Spinalis

Quadratuslumborum


Table 7-5 Muscles of the Spine


Axial Muscles of the Trunk (7-10)

• External and internal intercostals • Elevate and depress ribs, respectively

• Diaphragm • Muscle used for inhalation of breath

• External and internal obliques, and the transversus abdominis • Compress abdomen, can flex spine

• Rectus abdominis • Depresses ribs, flexes spine


Figure 7-15 Oblique and Rectus Muscles and the Diaphragm.

Central tendonof diaphragm

Rectusabdominis

Xiphoidprocess

Externaloblique

Inferiorvena cava

T10

Erector spinae groupSpinal cord

Aorta

Diaphragm

Serratusanterior

Esophagus

Internalintercostal

Externalintercostal

Superior view at the levelof the diaphragm

Serratusanterior

Internal intercostal

External intercostal

External oblique(cut)

Internal oblique

Rectus abdominis

Anterior view

Linea alba(midline band

of denseconnective

tissue)

Aponeurosis

Externaloblique

Rectus abdominis

ExternalobliqueTransversusabdominisInternaloblique

Horizontal section view atthe level of the umbilicus

Quadratuslumborum

Linea alba

L3


Table 7-6 Axial Muscles of the Trunk


Muscles of the Pelvic Floor (7-10)

• Form the perineum and support the organs of the

pelvic cavity

• Flex the coccyx

• Control materials moving through the anus and

urethra with sphincters


Figure 7-16 Muscles of the Pelvic Floor.

Superficial Dissections Deep Dissections

Urethra

Ischiocavernosus

External urethral sphincter

Bulbospongiosus

Central tendon of perineum

Vagina

Transverseperineus

Levator ani

External anal sphincter

Gluteus maximus

Female

Testis

No differences betweendeep musculature inmale and female

Urethra (connectingsegment removed)

IschiocavernosusBulbospongiosus

Transverseperineus

Anus

Gluteus maximus

External urethral sphincter

Central tendon of perineum

Levator ani

External anal sphincter

Male

Anus


Table 7-7 Muscles of the Pelvic Floor


Checkpoint (7-10)

25. If you were contracting and relaxing your masseter muscle, what would you probably be doing?

26. Which facial muscle would you expect to be well developed in a trumpet player?

27. Damage to the external intercostal muscles would interfere with what important process?

28. If someone were to hit you in your rectus abdominis, how would your body position change?


Appendicular Muscles (7-11)

• Muscles that position the pectoral girdle

• Muscles that move the arm, forearm, and wrist

• Muscles that move the hand and fingers

• Muscles of the pelvic girdle

• Muscles that move the thigh and leg

• Muscles that move the foot and toes


Muscles That Position Pectoral Girdle (7-11)

• Trapezius

• Diamond-shaped muscle, has many actions depending on the region

• Rhomboid

• Adducts and rotates scapula laterally

• Levator scapulae

• Adducts and elevates scapula

• Serratus anterior

• Abducts and rotates scapula

• Pectoralis minor and subclavius

• Depress and abduct shoulder


Figure 7-17 Muscles That Position the Pectoral Girdle.

Superficial Dissection Deep Dissection

Muscles That Positionthe Pectoral Girdle

TrapeziusLevator scapulae

Rhomboid muscles

Serratus anterior

Tricepsbrachii

Posterior view

Trapezius Levator scapulae

SubclaviusPectoralis minor

Pectoralis major(cut and reflected)

Internal intercostals

External intercostals

Pectoralis minor(cut)Serratus anterior

Biceps brachii

Anterior view




Scapula

T12 vertebra


Table 7-8 Muscles That Position the Pectoral Girdle


Muscles That Move the Arm (7-11)

• Deltoid • Abducts arm, supraspinatus assists

• Subscapularis, teres major, infraspinatus, and teres minor • Form the rotator cuff

• Pectoralis major • Flexes the arm at the shoulder

• Latissimus dorsi • Extends the arm at the shoulder

A&P FLIX™ Rotator cuff muscles: An overview (b)PLAYPLAY

A&P FLIX™ Rotator cuff muscles: An overview (a)PLAYPLAY


Figure 7-18 Muscles That Move the Arm.

Anterior view


Sternum

Clavicle Ribs (cut)

Muscles ThatMove the Arm

SubscapularisCoracobrachialisTeres major

Biceps brachii

Vertebra T12

Deltoid

Latissimus dorsi

SupraspinatusInfraspinatusTeres minorTeres major

Triceps brachii

Pectoralis major




SupraspinatusDeltoid


Posterior view

Vertebra T1


Table 7-9 Muscles That Move the Arm


Muscles That Move the Forearm and Wrist (7-11)• Biceps brachii

• Flexes the elbow and supinates forearm

• Triceps brachii • Extends elbow

• Brachialis and brachioradialis • Flex elbow

• Flexor carpi ulnaris, flexor carpi radialis, and palmaris longus • Flex wrist

• Extensor carpi radialis and extensor carpi ulnaris • Extend wrist

• Pronators and supinators • Rotate radius


Muscles That Move the Hand (7-11)

• Extensor digitorum • Extends fingers

• Flexor digitorum • Flexes fingers

• Abductor pollicis • Abducts thumb

• Extensor pollicis • Extends thumb

A&P FLIX™ The elbow joint and forearm: An overviewPLAYPLAY


Figure 7-19 Muscles That Move the Forearm and Wrist.

Triceps brachii

Brachioradialis

Extensorcarpi radialis

Extensorcarpi ulnaris Extensordigitorum Abductorpollicis

Extensorpollicis

Extensor retinaculum

Flexordigitorum

superficialis

Flexorretinaculum Pronator

quadratus

Flexor carpiulnaris

Palmaris longus

Humerus

Coracobrachialis

Biceps brachii

Pronator teres

Flexorcarpi

ulnaris

Ulna

Brachioradialis

Brachialis

Flexor carpiradialis

SupinatorPronator

teres

UlnaRadius

Posterior view of right upper limb

Anterior view of right upper limb

Anterior view of themuscles of pronationand supination whenthe limb is supinated


Table 7-10 Muscles That Move the Forearm, Wrist, and Hand (1 of 2)


Table 7-10 Muscles That Move the Forearm, Wrist, and Hand (2 of 2)


Checkpoint (7-11)

29. Which muscle do you use to shrug your

shoulders?

30. Sometimes baseball pitchers suffer rotator cuff

injuries. Which muscles are involved in this type

of injury?

31. Injury to the flexor carpi ulnaris would impair

which two movements?


Muscles That Move the Thigh (7-11)

• Gluteal group

• Includes gluteus maximus, the largest and most posterior; is a hip extensor

• Adductors

• Include the adductor magnus, adductor brevis, adductor longus, the pectineus, and the gracilis

• Largest hip flexor is the iliopsoas

• Made up of the psoas major and the iliacus

A&P FLIX™ Anterior muscles that cross the hip jointPLAYPLAY


Figure 7-20 Muscles That Move the Thigh.

Iliac crestGluteus

medius (cut)Gluteus

maximus(cut)

SacrumGluteal Group

Gluteus maximusGluteus medius

Gluteus minimusTensor fasciae

lataeIliotibial tract

Vastus lateralis

Biceps femoris

SemimembranosusPlantaris

Head of fibula

Patella

PatellarligamentLateral

viewIliopsoas GroupPsoas major

Iliacus

PectineusAdductor brevisAdductor longus

Adductor magnusGracilis

Sartorius

Rectusfemoris

Gluteal region, posterior view

Adductor Group

Anterior view of the iliopsoas muscle and the adductor group

5L


Table 7-11 Muscles That Move the Thigh (1 of 3)






Muscles That Move the Leg (7-11)

• Knee flexors are the hamstrings

• Biceps femoris, semimembranosus, semitendinosus, and

the sartorius

• Knee extensors are the quadriceps femoris

• Which include the rectus femoris and the three vastus

muscles

• Popliteus muscle

• Unlocks the knee joint


Figure 7-21 Muscles That Move the Leg.

Iliac crest

Gluteus medius

Tensor fasciaelatae

Gluteus maximus

Adductor magnus

Gracilis

Iliotibial tract

Flexors of the Knee

Biceps femoris

Semitendinosus

Semimembranosus

Sartorius

Popliteus

IliacusPsoas major Iliopsoas

Tensor fasciaelatae

Pectineus

Adductor longus

Gracilis

Sartorius

Extensors of the Knee(Quadriceps muscles)

Rectus femoris

Vastus lateralis

Vastus medialisVastus intermedius(deep to above muscles)

Quadriceps tendon

Patella

Patellar ligament

Hip and thigh, posterior view Quadriceps and thigh muscles, anterior view


Table 7-12 Muscles That Move the Leg


Muscles That Move the Foot and Toes (7-11)

• The gastrocnemius of the calf is assisted by the

underlying soleus

• They share a common calcaneal tendon, and are both

plantar flexors

• Fibularis muscles

• Produce eversion and plantar flexion

• Tibialis

• Cause inversion of the foot

• Tibialis anterior is largest and produces dorsiflexion


Figure 7-22a Muscles That Move the Foot and Toes.


Ankle Extensors

Plantaris

Gastrocnemius

Soleus

Gastrocnemius(cut and removed)

Popliteus

Tendon of flexorhallucis longus

Calcanealtendon

Calcaneus

Head of fibula

Ankle Extensors(Deep)

Tibialis posterior

Fibularis longus

Fibularis brevis

Digital Flexors

Flexor digitorumlongus

Flexor hallucislongus

Tendon of flexor digitorumlongus

Tendons of fibularismuscles

Posterior views


Iliotibial tract

Head of fibula

Ankle Extensors

Ankle FlexorsGastrocnemius

Fibularis longus

Soleus

Fibularis brevis

Tibialis anterior

Extensor digitorumlongus

Tendon of extensorhallucis longusCalcaneal tendon

Retinacula

Lateral view

Digital Extensors

Figure 7-22b Muscles That Move the Foot and Toes.


Figure 7-22c Muscles That Move the Foot and Toes.

Patella

Patellarligament

Medial surfaceof tibial shaft

Ankle Extensors

Gastrocnemius

Soleus

Tibialis posterior

Calcaneal tendon

RetinaculaTendon of

tibialis anterior

Medial view

Ankle Flexors

Tibialis anterior

Tendon of extensorhallucis longus

Digital Extensors


Table 7-13 Muscles That Move the Foot and Toes (1 of 2)


Table 7-13 Muscles That Move the Foot and Toes (2 of 2)


Checkpoint (7-11)

32. You often hear of athletes suffering a "pulled

hamstring." To what does this phrase refer?

33. How would you expect a torn calcaneal tendon

to affect movement of the foot?


Four Effects of Aging on Skeletal Muscle (7-12)

1. Muscle fibers become smaller in diameter

2. Muscles become less elastic and more fibrous

3. Tolerance for exercise decreases due to a

decrease in thermoregulation

4. Ability to recover from injury is decreased


Checkpoint (7-12)

34. Describe general age-related effects on skeletal

muscle tissue.


Exercise Engages Multiple Systems (7-13)

• Cardiovascular system

• Increases heart rate and speeds up delivery of oxygen

• Respiratory system

• Increases rate and depth of respiration

• Integumentary system

• Dilation of blood vessels and sweating combine to increase cooling

• Nervous and endocrine systems

• Control of heart rate, respiratory rate, and release of stored energy


Figure 7-23 SYSTEM INTEGRATORBody System Muscular System Muscular System Body System

Inte

gu

men

tary

Ske

leta

l

Removes excess body heat; synthesizes vitamin D3 for calcium and phosphate absorption; protects underlying muscles

Provides mineral reserve for maintaining normal calcium and phosphate levels in body fluids; supports skeletal muscles; provides sites of attachment

Skeletal muscles pulling on skin of face produce facial expressions

Inte

gu

men

tary

(Pag

e 1

38)

Provides movement and support; stresses exerted by tendons maintain bone mass; stabilizes bones and joints

Ske

leta

l(P

age

188

)

The MUSCULAR System

The muscular system performs five primary functions for the human body. It produces skeletal movement, helps maintain posture and body position, supports soft tissues, guards entrances and exits to the body, and helps maintain body temperature.

Ne

rvo

us

(Pag

e 3

02)

En

do

cri

ne

(Pag

e 3

76)

Car

dio

vasc

ula

r(P

age

467)

Ly

mp

hat

ic(P

age

500

)R

esp

ira

tory

(Pag

e 5

32)

Dig

esti

ve

(Pag

e 5

72)

Uri

na

ry(P

age

637

)R

ep

rod

uc

tiv

e(P

age

671

)


Checkpoint (7-13)

35. What major function does the muscular system

perform for the body as a whole?

36. Identify the physiological effects of exercise on

the cardiovascular, respiratory, and

integumentary systems, and indicate the

relationship between these physiological effects

and the nervous and endocrine systems.

Business

163 ch 07_lecture_presentation