1. Chapter 7 The Muscular System

2. The Muscular System
Muscles are responsible for all types of body movement – they contract or shorten and are the machine of the body
Three basic muscle types are found in the body
Skeletal muscle
Cardiac muscle
Smooth muscle

3. Characteristics of Muscles
Muscle cells are elongated (muscle cell = muscle fiber)
Contraction of muscles is due to the movement of microfilaments
All muscles share some terminology
Prefix myo refers to muscle
Prefix mys refers to muscle
Prefix sarco refers to flesh
Slide 6.2
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4. 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 = great force, but tires easily
Slide 6.3
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5. Connective Tissue Wrappings of Skeletal Muscle
Endomysium – around single muscle fiber
Perimysium – around a fascicle (bundle) of fibers
Figure 6.1
Slide 6.4a
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6. Connective Tissue Wrappings of Skeletal Muscle
Epimysium – covers the entire skeletal muscle
Fascia – on the outside of the epimysium
Figure 6.1
Slide 6.4b
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7. Skeletal Muscle Attachments
Epimysium blends into a connective tissue attachment
Tendon – attach muscle to bone
Ligaments – attach bone to bone
Sites of muscle attachment
Bones
Cartilages
Connective tissue coverings
Slide 6.5
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8. Smooth Muscle Characteristics
Has no striations
Involuntary – no conscious control
Found mainly in the walls of hollow organs
Push food along digestive tract
Contract uterus during childbirth
Control diameter of blood vessels
Slow, sustained and tireless (can remain contracted for long periods)
Slide 6.6
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9. Cardiac Muscle Characteristics
Has striations
Involuntary
Found only in the heart
Requires continuous oxygen supply
Steady pace!
Figure 6.2b
Slide 6.7
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10. Function of Muscles Produce movement Maintain posture Stabilize joints
Generate heat
Slide 6.8
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11. Microscopic Anatomy of Skeletal Muscle
Cells are multinucleate
Nuclei are just beneath the sarcolemma (cell membrane)
Figure 6.3a
Slide 6.9a
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12. Microscopic Anatomy of Skeletal Muscle
Sarcolemma – specialized plasma membrane
Sarcoplasmic reticulum – specialized smooth endoplasmic reticulum
Figure 6.3a
Slide 6.9b
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13. Characteristics of Muscles
Contractility – ability to shorten in response to a suitable stimulus
Excitability/Irritability – ability to receive and respond to a stimulus (produces electric signals/impulses)
Extensibility – ability to be stretched
Elasticity – ability to return to original length when relaxing
Slide 6.13
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14. Muscle Attachments & Functions
Muscles are attached to bones by tendons
Bones are connected to bones by ligaments

15. Muscle Attachments & Functions
When a muscle attaches to an immoveable bone, it is called the origin.
Attachment to the moveable bone is called the insertion.
Sternocleidomastoid
Origin: sternum & clavicle
Insertion: mastoid process

16. Example:
Origin of the shoulder muscle (deltoid) is by the clavicle and scapula.
Its insertion is on the humerus.
When the deltoid contracts, the area by the scapula remains stationary, but the area by the humerus moves and abducts the arm away from the body.

17. Types of Body Movements
Adduction – moving a body part toward the midline
Abduction – moving a body part away from the midline
Flexion – decreasing the angle between two bones, or bending a body part
Extension – increasing the angle between two bones, or straightening a body part
Rotation – turning a body part around its own axis (head from side to side)

20. Body Movements Slide 6.33 Figure 6.13
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21. 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
Slide 6.31
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22. Muscle Fatigue Caused by accumulation of lactic acid in the muscles
During period of vigorous exercise, the blood is unable to transport enough oxygen to meet demand
This causes the muscles to contract anaerobically lactic acid builds up in muscles.
Results in muscle fatigue and cramping

23. 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
Slide 6.35
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24. Naming of Skeletal Muscles
Location of the muscle
Example: many muscles are named for bones (e.g., temporalis)
Number of origins
Example: biceps (two headed muscle on humerus)
Slide 6.36b
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25. Naming of Skeletal Muscles
Direction of muscle fibers
Example: external abdominal oblique – edge of lower rib cage
Size of the muscle
Example: gluteus maximus (largest muscle in buttock)
Slide 6.36a
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26. Naming of Skeletal Muscles
Shape of the muscle
Example: deltoid (triangular)
Action of the muscle
Example: flexor and extensor (flexes or extends a bone)
Slide 6.37
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27. Head and Neck Muscles Slide 6.38 Figure 6.14
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28. Trunk Muscles Slide 6.39 Figure 6.15
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29. Deep Trunk and Arm Muscles
Figure 6.16
Slide 6.40
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30. Muscles of the Pelvis, Hip, and Thigh
Figure 6.18c
Slide 6.41
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31. Muscles of the Lower Leg
Figure 6.19
Slide 6.42
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32. Superficial Muscles: Anterior
Figure 6.20
Slide 6.43
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33. Superficial Muscles: Posterior
Figure 6.21
Slide 6.44
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