1. The Muscular System Unit Objectives:
Be able to explain the differences between the 3 types of muscles in the human body
Be able to describe common muscle actions and how muscle contractions are initiated
Be able to name the major skeletal muscles of the body (human and cat) as well as their origin/insertion points

2. The Muscular System
Muscles are responsible for all types of body movement
Muscle Functions:
Movement
Maintain posture
Stabilize joints
Heat
Three basic muscle types found in the body:
1-Smooth muscle
2-Cardiac muscle
3-Skeletal muscle

3. Characteristics of Muscles
Muscle cells are elongated
Contraction of muscles is due to the movement of microfilaments – many cells contracting at the same time
All muscles share some terminology
Prefix myo refers to muscle

4. 1-Smooth Muscle Characteristics: How blood and food move
No striations
Spindle-shaped cells
Single nucleus
Involuntary – no conscious control
Found mainly in the walls of hollow organs (blood vessels, intestines)
Figure 6.2a

5. 2-Cardiac Muscle Characteristics: What makes your heart beat?
Striations
Usually only one nucleus
Cells joined to each other at an intercalated disc
Involuntary
Found only in the heart
Figure 6.2b

6. 3-Skeletal Muscle Characteristics: Moving your bones!
Most are attached by tendons to bones
Remember “tendons tug”
Cells have more than one nucleus
Striated – have visible banding
Voluntary – subject to conscious control
Cells are surrounded and bundled by connective tissue

7. Connective Tissue Wrappings of Skeletal Muscle
Endomysium – around single muscle fiber
Perimysium – around a bundle of fibers
Epimysium – covers the entire skeletal muscle
Fascia – on the outside of the epimysium
Figure 6.1

9. Skeletal Muscle Attachments
Epimysium blends into a connective tissue attachment; the tendon – a cord-like structure
Sites of muscle attachment
1-Bones
2-Cartilages
3-Connective tissue coverings
Animation: online.com/objects/index_tj.asp?objID=AP13904

10. Contraction of a Skeletal Muscle
Video
Muscle fiber contraction is “all or none”
Within a skeletal muscle, not all fibers may be stimulated during the same interval
Different combinations of muscle fiber contractions may give differing responses
Graded responses – different degrees of skeletal muscle shortening
Must have ATP in order to contract

11. Muscle Response to Strong Stimuli
Muscle force depends upon the number of fibers stimulated
More fibers contracting results in greater muscle tension
Muscles can continue to contract unless they run out of energy (ATP) :(

12. Energy for Muscle Contraction
Initially, muscles used stored ATP for energy – aerobic activities
Bonds of ATP are broken to release energy
Only 4-6 seconds worth of ATP is stored by muscles
After this initial time, other pathways must be utilized to produce ATP – anaerobic activities and lactic acid build-up

13. Muscle Fatigue and Oxygen Debt
When a muscle is fatigued, it is unable to contract
The common reason for muscle fatigue is oxygen debt
Oxygen must be returned to tissue to remove oxygen debt
Oxygen is required to get rid of accumulated lactic acid
Increasing acidity (from lactic acid) and lack of ATP causes the muscle to contract less

14. Muscles and Body Movements
Movement is attained due to a muscle moving an attached bone
Muscles are attached to at least two points
Origin – attachment to an immoveable bone
Insertion – attachment to a movable bone
Figure 6.12

15. Ordinary Body Movements
Flexion – decreases the angle between two adjacent body segments
Extension – increases the angle between two adjacent body segments
Rotation – the bone distal to the joint is moved either toward (medial) or away from (lateral) the midline
Abduction – movement of a body part away from the midline
Adduction – movement of a body part back toward the midline
Circumduction – a combination of flexion, abduction, extension, and adduction

16. Body Movements
Figure 6.13a–c

17. Body Movements

18. Body Movements
Figure 6.13d

19. Naming of Skeletal Muscles
1-Direction of muscle fibers
Example: rectus (straight)
2-Relative size of the muscle
Example: maximus (largest)
3-Location of the muscle
Example: many muscles are named for bones (e.g., temporalis)
4-Number of origins
Example: triceps (three heads)

20. Naming of Skeletal Muscles
5-Location of the muscle’s origin and insertion
Example: sterno (on the sternum)
6-Shape of the muscle
Example: deltoid (triangular)
7-Action of the muscle
Example: flexor and extensor (flexes or extends a bone)

21. Head and Neck Muscles
Figure 6.15

22. Trunk Muscles
ANTERIOR
Figure 6.16

23. Deep Trunk and Arm Muscles
POSTERIOR
Figure 6.17

24. Muscles of the Pelvis, Hip, and Thigh
Figure 6.19c

25. Muscles of the Lower Leg
POSTERIOR
ANTERIOR
Figure 6.20

26. Superficial Muscles: Anterior
Figure 6.21

27. Superficial Muscles: Posterior
Figure 6.22

28. Movement Quiz:
Standing on your toes as in ballet is (1) of the foot. Walking on your heels is (2) .
Winding up for a pitch (as in baseball) can properly be called (3) . To keep your seat when riding a horse, the tendency is to (4) your thighs.
In running, the action at the hip joint is (5) in reference to the leg moving forward and (6) in reference to the leg in the posterior position. When kicking a football, the action at the knee is (7) . In climbing stairs, the hip and knee of the forward leg are both (8) .

29. You have just touched your chin to your chest; this is. (9)
You have just touched your chin to your chest; this is (9) of the neck.
Using a screwdriver with a straight arm requires (10) of the arm. Consider all the movements of which the arm is capable. One often used for strengthening the upper arm and shoulder muscles is (11) .
Moving the head to signify “no” is (12) . Action that moves the distal end of the radius across the ulna is (13) . Raising the arms laterally away from the body is called (14) of the arms.When you are cupping your hands in order to hold a bowl of soup, the position is called __(15)__.

30. CREATE MOVEMENT POSTER IN GROUPS!!