Unit 5 Muscular System

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1

Unit 4
The Muscular System
Hilario Cruzada Noveno Jr.
Lecturer [

]

The Muscular System
• Muscles are responsible for all types of body
movement (
)
• Three basic muscle types are found in the
body (
)
– Skeletal muscle (
– Cardiac muscle (
– Smooth muscle (

)
)

)

3

Three basic muscle types
are found in the body (

)


4

Characteristics of Muscles
[
]
• Muscle cells are elongated (
)
(muscle cell = muscle fiber)
• Contraction of muscles is due to the
movement of microfilaments
(
microfilaments)


5

Characteristics of Muscles
[
]
• All muscles share some terminology (
)
– Prefix myo refers to muscle (
)
– Prefix mys refers to muscle (MYS
)
– Prefix sarco refers to flesh (


)

6

Skeletal Muscle Characteristics
[
]
• Most are attached by tendons to bones
(
)
• Cells are multinucleate (
)
• Striated (
) – have visible banding
(
)
• Voluntary (
) – subject to conscious control
(
)
• Cells are surrounded and bundled by connective
tissue (
)

7

• Fascia (
) – on the
outside of the epimysium
(
)

Connective Tissue Wrappings of Skeletal Muscle

[

]

• Epimysium ( ) – covers the
entire skeletal muscle
(
)
• Perimysium (
)–
around a fascicle (bundle) of
fibers (
)
• Endomysium (
)–
around single muscle fiber ( -)


8

Skeletal Muscle Attachments
[
]
• Epimysium blends into a • Sites of muscle
connective tissue
attachment
attachment
(
(
– Bones (
)
)
– Cartilages (
– Tendon ( ) – cord-like
structure (
)
– Aponeuroses (
)–
sheet-like structure
(
)

)
)

– Connective tissue
coverings (
)


9

Smooth Muscle Characteristics
[
]
•
•
•
•

Has no striations (
)
Spindle-shaped cells (
)
Single nucleus (
)
Involuntary (
) – no conscious control
(
)
• Found mainly in the walls of hollow organs
(
)


10

Smooth Muscle Characteristics
[
]


11

Cardiac Muscle Characteristics
[
]
• Has striations (
)
• Usually has a single nucleus (
)
• Joined to another muscle cell at an
intercalated disc (
)
• Involuntary (
)
• Found only in the heart (

)
12

Cardiac Muscle Characteristics
[
]


13

CHARACTERISTIC

SKELETAL

CARDIAC

SMOOTH

Special Features

None

Intercalated discs

Cell-cell attachment

Nucleus

Multinucleate

Striation

Mononucleate
Yes

No

Cell shape

Long, cylinrical

Movement

Voluntary

Involuntary

Innervation

Somatic NS

Autonomic NS

Location

Attached to bone

Function

Branched

Spindle

Heart

Move bodyh_noveno@hotmail.com contraction
Cardiac

Walls of hollow
organs

Compression of
organs, ducts,15
ect

Function of Muscles
[
]
• Produce movement (

)

• Maintain posture (

)

• Stabilize joints (

• Generate heat (

)

)

16

Microscopic Anatomy of Skeletal Muscle
[
]

Cells are multinucleate (
Nuclei are just beneath the sarcolemma (

)
)
27

[
]

Sarcolemma (
Sarcoplasmic reticulum (
(

) – specialized plasma membrane (
)
) – specialized smooth endoplasmic reticulum
)

28

[
]
Myofibril
Bundles of myofilaments (
myofilaments)
Myofibrils are aligned to give distinct bands (
)
I band (
I) = light band (
)
A band ( ) = dark band (
)


29

[
]
Sarcomere (
muscle fiber (

): Contractile unit of a
)


30

[
]
Organization of the sarcomere (
)
Thick filaments (
) = myosin filaments
(
)
Composed of the protein myosin (
)
Has ATPase enzymes (
)


31

[
]
Organization of the sarcomere (
)
Thin filaments (
) = actin filaments
(
)
Composed of the protein actin (
)


32

[
]
• Myosin filaments have heads
(
): extensions, or cross
bridges (
)

• Myosin and actin overlap somewhat
(
)


33

[
]


34

[
]
• At rest, there is a bare zone that lacks actin
filaments (
)

• Sarcoplasmic reticulum (
for storage of calcium (


)–
)

35

[
]


36

Properties of Skeletal Muscle Activity
[
]
• Irritability (
) – ability to receive and
respond to a stimulus (
)

• Contractility (
) – ability to shorten when
an adequate stimulus is received (
)


37

Properties of Skeletal Muscle Activity
[
]
• Skeletal muscles must be
stimulated by a nerve to
contract (
)
• Motor unit (

)

– One neuron (
)
– Muscle cells stimulated by
that neuron (
)


38

Nerve Stimulus to Muscles
[
]
• Neurotransmitter (
) – chemical released by
nerve upon arrival of nerve impulse (
)
– The neurotransmitter for skeletal muscle is
acetylcholine (

)

• Neurotransmitter attaches to receptors on the
sarcolemma (
)
• Sarcolemma becomes permeable to sodium (Na+)
(
)

39

Nerve Stimulus to Muscles
[
]


40

Neuromuscular Junction

Skeletal Muscle Contraction

Types of Muscle Contractions
[
]
Isotonic contractions
(
)
• Myofilaments are able to
slide past each other during
contractions
(Myofilaments
)

Isometric contractions
(
)
• Tension in the muscles
increases (
)
• The muscle is unable to
shorten (
)

• The muscle shortens
(
)


42

Muscle Tone [

]

• Some fibers are contracted even in a relaxed
muscle (
)
• Different fibers contract at different times to
provide muscle tone (
)
• The process of stimulating various fibers is under
involuntary control (
)

43

Muscles and Body Movements
[
]
• Movement is attained due to a muscle moving
an attached bone (
)


44

Skeletal Muscle
[

]

45

Muscles and Body Movements
[
]
• Muscles are attached to at least two points
(
)
– Origin (
) – attachment to a moveable bone
(
)
– Insertion (
) – attachment to an immovable
bone (
)


46

Effects of Exercise on Muscle
[
]
• Results of increased muscle use
(
)
– Increase in muscle size (
– Increase in muscle strength (
– Increase in muscle efficiency (
– Muscle becomes more fatigue resistant
(
)


)
)
)

47

Types of Muscles
[
]
• Prime mover (
) – muscle with the major
responsibility for a certain movement (
)
• Antagonist (
) – muscle that opposes or reverses a
prime mover (
)
• Synergist (
) – muscle that aids a prime mover in a
movement and helps prevent rotation (
)
• Fixator – stabilizes the origin of a prime mover
(
)


48

Naming of Skeletal Muscles
[
]
• Direction of muscle fibers (
– Example (
]

)

): rectus (straight) [

– Rectus abdominis
– Transversus abdominis
– Internal oblique
– External oblique

49

[
]
• Relative size of the
muscle (
)
– Example (
(largest)
[

): maximus

]


50

[
]
• Location of the muscle
(
)
– Example ( ): many
muscles are named for
bones (e.g., temporalis)
[
]


51

[
]
• Number of origins
(
)
– Example ( ): triceps
(three heads) [
]


52

[
]
• Location of the muscles
origin and insertion
(
)
– Example ( ): sterno
(on the sternum)


53

[
]
• Shape of the muscle
(
)
– Example ( ): deltoid
(triangular)
[
]


54

[
]
• Action of the muscle
(
)
– Example ( ): flexor and
extensor (flexes or extends a
bone)
[
]


55

Head and Neck Muscles
[
]


56

Trunk Muscles
[
]


57

Deep Trunk and Arm Muscles
[
]


58

Muscles of the Pelvis, Hip, and Thigh

[

]


59

Muscles of the Lower Leg

[

]


60

Superficial Muscles: Anterior
[
]


61

Superficial Muscles: Posterior

[

]


62

Types of Ordinary Body Movements
[
]
•
•
•
•
•

Flexion (
)
Extension (
)
Rotation (
)
Abduction (
)
Circumduction (

)


63

MUSCULAR LABORATORY


64

Body Movements
[
]


65

Body Movements
[
]


66

Body Movements
[
]


67

Special Movements
[
]
•
•
•
•
•
•
•

Dorsiflexion (
)
Plantar flexion (
)
Inversion (
)
Eversion (
)
Supination (
)
Pronation ( )
Opposition (
)

68

Unit 5 Muscular System

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