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Topic 9: Myology

� What are the different muscle types?

� Morphology & location

� Physiology

� How do muscles develop?

� What do muscles look like at the cellular level?

� How do muscles contract?

� How do whole muscles work?

� How are muscles functionally divided?

� Human facial expression

What are the different muscle types?

Liem et al. Fig. 10-1; www.cytochemistry.net

_______

Muscle

_______

Muscle

_______

Muscle

Skeletal muscle,

attached to bones

Hearth muscle

-Unitary: visceral

organs

-Multiunit: iris &

blood vessels

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Liem et al. Fig. 10-1

Striated Muscle Cardiac Muscle Smooth Muscle

Cell Size Small, elongate Small, elongate

# nuclei Many Single Single

Control Voluntary Involuntary Involuntary

Stimulus Unitary: myoMultiunit: neuro

Contraction Force

Contraction Rate Slow to fast Moderate Relatively slow

Fatigue Fatigues Does not Does not

What are the different muscle types?

How do muscles develop?

Wolpert, 1998

Mesoderm

Paraxial

Kidneys

Somatic

Lateral PlateIntermediate

SplanchnicMyotome

Visceral

Muscles

Body

Wall

Muscles

Limb

Muscles

Dermatome

Sclerotome

Heart

What type of muscle makes up each of these?

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What kind of cell anatomy do muscles have?

Liem et al. Fig. 10-2

• Muscle

– Epimysium

– _____________• Perimysium

• _________________

– Endomysium

– Capillaries

– ____________

Liem et al. Fig. 10-2

� Myofibrils composed of

________________

� Sarcomere components

� ____________: Thick

� ____________: Thin

� Tropomyosin: Binds actintogether

� Overlap of proteins in a sarcomere produces a

banding pattern

� Z line: Edge of sarcomere

� I band: Actin only

� A band: Actin & myosin

� H zone: Myosin onlyLiem et al. Fig. 10-2

What kind of cell anatomy do muscles have?

How do muscles contract?

� Tension-Length curve for a ___________

� Myosin heads move along actin units

Liem et al. Fig. 10-2, Focus 10-1

Force

Muscle Fiber Length

� Maximum force:

� All myosin heads are deployed

� Actin filaments do not overlap

� Tension-length curve differs for whole muscle

� Total Tension = _________ Tension + _________ Tension

� Why?

Liem et al. Focus 10-2

Force

Muscle Fiber Length

How do muscles contract?

Types of Muscle Contraction

� _____________

� Contraction under constant load

� Load stays the same

� Muscle length changes

� _____________

� Contraction under constant length

� Load changes

� Muscle length stays the same

� What are examples of exercises that are isotonic and isometric?

www.thefreedictionary.com

Types of Muscle Contraction

� Under isometric contraction

� Single neural stimulus

� ____________ period

� ____________ period

� Relaxation period

Liem et al. Fig. 10-4

Tension/Force

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Types of Muscle Contraction

� Shape of tension-length curve changes with number of stimuli

� Latent period

� Contraction period

� Relaxation period

Liem et al. Fig. 10-4

Tension/Force

Time (ms)

Tetanic Fusion

What types of muscle

fibers are there?

© KE Bonine

Slow Oxidative Fast Glycolytic

Metabolism

Mitochondria Many Fewer

Glycogen Little Lots

Color Red (black in figure) White (& in figure)

Contraction

Fatigue Do not fatigue Fatigue quickly

Use Endurance,sustained

actions

Bursts, short & powerful

actions

Fast Oxidative Glycolytic fibers are intermediate

Muscle Architecture

� Broad vs tendinous attachment

� Longer & faster contractions

� Bigger movements

� Lower force generation

� Force diffuse vs focusedLiem et al. Fig. 10-6

_________ Fusiform _________ Bipinnate

� Tendinous attachment

� Shorter & slower contractions

� Smaller movements

� High force generation

- Examples? Muscle Attachments

� Origin – Attachment at the unmoving end of the muscle

� Insertion – Attachment at the moving

end of the muscle

� Action – The resulting movement

� Some actions

� Muscles can

be synergistic or antagonistic

Liem et al. Fig. 10-3

Motion

� Elucidating muscle action

� m. tensor fascia latae and

iliotibial band

� What is its origin?

� What is its insertion?

� What is its muscle fiber direction?

� What is its action?

� Other actions:� ___________ & ___________

� Collapse of arch

� Rolling the ankle

Kardong Fig. 4-37; www. thestretchinghandbook.com

Medial Medial

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How are muscles functionally divided?

� Trunk musculature

� ________ & _________

� ________ & _________

� Appendicular musculature

� Dorsal & Ventral

� Pairs of groups have different innervations

� What does each group develop from?

Liem et al. Fig. 10-8

� Trends in axial musculature evolution� ________________

� ________________

� ________________ of function (muscle fiber direction)

Liem et al. Fig. 10-16, 10-18

Fish

SalamanderLizard

How have the trunk

muscles evolved?

Liem et al. Fig. 10-20, 10-21

� Similar trends in limb musculature evolution� Duplication

� Differentiation

� Specialization of function (muscle fiber direction)

Fish

Lizard

Cat

How have limb

muscles evolved? Platysma and Facial Muscles

� Derived from hyoid muscles

� Form lips & cheeks

� Coupled with evolution of nipples

� What are actions of:

� Frontal muscle

� m. orbicularis oculi

� m. orbicularis oris

� m. quadratus labii superior

Liem et al. Fig. 10-14