1. Chapter 5
Muscular System

2. MUSCLES Approximately 40% of your body weight
Approximately 650 muscles
Muscles only pull (they can’t push)
You have over 30 facial muscles
Eye muscles move more than 100,000 times a day

3. Overview of Muscle Tissues
Consists of muscle cells that are highly specialized for contraction
Muscle is the dominant tissue in the heart and in the walls of other hollow organs of the body.
Essential function of muscle is contraction, or shortening – a unique characteristic that sets it apart from any other body tissue
Muscles are responsible for essentially all body movement and can be viewed as the “machines” of the body.

4. There are 3 types of muscle tissue
Skeletal
Cardiac
Smooth

5. Skeletal Muscle Functions
Muscle plays six important roles in the body:
Produce skeletal movement
Maintains posture and body position
Support soft tissues (abdominal wall & pelvic cavity)
Guard entrances and exits (digestive and urinary tracts)
Maintain body temperature (energy is converted to heat)
Store nutrient reserves (proteins are broken down & amino acids are used)

6. Organization of Muscle Tissue
Three layers of connective tissue are part of each muscle:
Epimysium – dense layer of collagen fibers that surround the entire muscle
Perimysium – divides the muscle into a series of compartments each containing a bundle of muscle fibers (fascicle); contains collagen & elastic fibers, blood vessels and nerves that maintain blood flow
Endomysium – flexible, elastic connective tissue layer; surrounds the individual skeletal muscle cells and interconnects adjacent muscle fibers

7. Arrangement of Fascicles
Parallel - fascicles run parallel to the long axis of the muscle
*Most skeletal muscles are parallel muscles
Fusiform – spindle-shaped muscles
Figure 10.1

8. Arrangement of Fascicles
Pennate – the fascicles form a common angle with the tendon (rectus femoris and deltoid)
Convergent – fascicles converge on a common attachment site (pectoralis major)
Figure 10.1

9. Arrangement of Fascicles
Circular – fascicles are arranged in concentric rings around an opening (orbicularis oris)
Figure 10.1

10. Axial and Appendicular Muscles
Axial muscles arise on the axial skeleton (60% of skeletal muscles) ; position the head and spinal column and move the rib cage
Appendicular muscles stabilize and move the appendicular skeleton (40% of skeletal muscles)

11. Naming of Skeletal Muscles
Direction of muscle fibers
Example: rectus (straight)
Relative size of the muscle
Example: maximus (largest)
Slide 6.36a
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12. Naming of Skeletal Muscles
Location of the muscle
Example: many muscles are named for bones (e.g., temporalis)
Number of origins (where fixed end attaches to a bone, cartilage or connective tissue)
Example: triceps (three heads)
Slide 6.36b
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13. Naming of Skeletal Muscles
Location of the muscles origin and insertion (movable end attaches to another structure)
Example: sterno (on the sternum)
Shape of the muscle
Example: deltoid (triangular)
Action of the muscle
Example: flexor and extensor
Slide 6.37
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14. Head and Neck Muscles Figure 6.14 Slide 6.38
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15. Trunk Muscles Figure 6.15 Slide 6.39
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16. Deep Trunk and Arm Muscles
Figure 6.16
Slide 6.40
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17. Muscles of the Pelvis, Hip, and Thigh
Figure 6.18c
Slide 6.41
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18. Muscles of the Lower Leg
Figure 6.19
Slide 6.42
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19. Superficial Muscles: Anterior
Figure 6.20
Slide 6.43
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20. Superficial Muscles: Posterior
Figure 6.21
Slide 6.44
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21. Types of Ordinary Body Movements
Flexion – bending at the joint
Extension - straightening at the joint
Hyperextension
Rotation – rotating on axis
Abduction – moving away from the midline
Adduction – moving toward the body
Circumduction – circular movement
Slide 6.32
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22. Body Movements Figure 6.13 Slide 6.33
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23. Special Movements
Dorsifelxion
Plantar flexion

24. Special Movements Inversion Eversion Slide 6.34
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25. Special Movements
Opposition
Supination
Pronation

26. Three Types of Contractions/Exercises
Antagonistic muscles – work in opposition
Example: bicep & tricep (flexor/extensor)
Three Types of Contractions/Exercises
These contractions provide resistance to make the muscle work harder for the purpose of developing muscular fitness:
1. Isometric
2. Isotonic
3. Isokinetic

27. Contract or tighten muscles but fibers do not change length
Isometric
Static contractions
Contract or tighten muscles but fibers do not change length
There is no movement of the joint to which the muscle is attached
Examples:
Block tackle in football
Weight – lifter holds barbell above head

28. Isotonic
Most common type of contraction
The muscle either shortens (concentric) or lengthens (eccentric) and takes a joint through a full range of motion (ROM) by raising and lowering a fixed resistance
Examples: Raising and lowering a weight

29. Isokinetic
A muscle shortens at constant speed over the full range of motion
Perform by using special equipment that contains a speed governor so that the speed of the movement is constant no matter how much tension is produced by the muscle
Example:
Rowing machine

30. Strain vs. Sprain
What is a strain? Strains are injuries that involve the stretching or tearing of a musculo-tendinous (muscle and tendon) structure What is a sprain? A sprain is an injury involving the stretching or tearing of a ligament (tissue that connects bone to bone) or a joint capsule

31. Sprains and Strains are categorized according to severity.
Grade I (mild) sprain or strain involves some stretching or minor tearing of a ligament or muscle.
Grade II (moderate) sprain or strain is a ligament or muscle that is partially torn but still intact.
Grade III (severe) sprain or strain means that the ligament or muscle is completely torn, resulting in joint instability.

32. Ankle Sprains

34. Examples of Strains

35. First Aid
R – rest
I - ice
C - compression
E - elevation

36. Information obtained from: http://www.mda.org/disease/dmd.html
Duchenne Muscular Dystrophy (DMD)
Definition - One of nine types of muscular dystrophy, a group of genetic, degenerative diseases primarily affecting voluntary muscles.
Cause - An absence of dystrophin, a protein that helps keep muscle cells intact.
Information obtained from:

37. DMD continued..... Onset - Early childhood - about 2 to 6 years.
Symptoms - Generalized weakness first affecting the muscles of the hips, pelvic area, thighs and shoulders. Calves are often enlarged.
Progression - DMD eventually affects all voluntary muscles, and the heart and breathing muscles.
Inheritance - X-linked recessive. DMD primarily affects boys, who inherit the disease through their mothers. Women can be carriers of DMD but usually exhibit no symptoms.