Muscles

1. Muscles

2. Function of Muscle • Muscle tissue is responsible for all body movements. This includes body motion as in walking but also organ movement such as dilation of blood vessels or heart contraction. • Muscles support the functions of most our systems that keep us alive: ie – respiration, digestion, blood circulation … • Heating of body, muscle contractions give off heat and help maintain body temperature. Shivering warms the body when muscles in the skin contract reflexively due to cold.

3. How Many?? • There are over 600 different muscles in our body. Some are very large for gross motor movement (kicking a ball) and some very tiny fine motor control (blinking).

4. Muscle TissueSkeletal, Cardiac and Smooth

5. Anatomy of a Skeletal MuscleSkeletal muscle attaches to bone and moves our skeleton

6. Cardiac Muscle • Found only in the heart. Able to contract independently of the brain but requires signals from the brain to beat in correct sinus rhythm.

7. Smooth Muscle tissue is found in the organs and vessels of the body.

8. Muscle Fibers • Muscle Fibers are about the diameter of a human hair, they can contract about ½ their length and can lift about 1000 times their weight. • Muscle Fibers can stretch, contract but need to be pulled back by another force to return to their original length.

9. Muscle PairsAgonist and Antagonist • Example – Arm Flexors and Extensors are paired to move the flex (bend) and extend (straighten) the arm. Muscles work in pairs to counteract each other’s movement

10. Eccentric, Concentric and IsometricContractions

11. Tendons, Origin and Insertion • Tendons connect the muscle to bone. • Origin is the connection we call an anchor, it does not move during the contraction • Insertion is the connection that moves a bone during the contraction.

12. Motor Unit A motor unit consists of the nerve (neuron) and all the fibers connected to it. When a neuron is stimulated all of its fibers will contract completely. This called the All or None Principal

13. Gross Motor MovementsBig muscles with small # of motor units but each motor unit controls large numbers of muscle fibers

14. Fine Motor • Small muscles with lots of motor units to control them but each motor unit controls small numbers of muscle fibers.

15. Muscle Strength • Muscles can adapt to use. Muscle fibres get thicker and stronger if they are exercised regularly over time.

16. Flexibility – muscles will lengthen if stretched regularly over time. Better flexibility reduces risk of muscle injuries

17. Muscle Concepts • Transient Hypertrophy – Muscle temporarily get larger during exercise due to increased blood flow. This lasts only for 30 minutes or so after exercise. Does not increase strength. • Chronic Hypertrophy – Muscle fibers diameters get bigger as they adapt to repeated exercise training. As fibers get larger the muscle gets bigger and stronger over time. • Muscle Atrophy - Muscle fiber diameters get smaller over time as a result of lack of use or training. Results in loss of strength. • Hyperplasia – An unproven theory that increases in strength due to exercise actually result in muscle fibers splitting and increasing in number to account for increased strength. • Voluntary Muscle – muscles that we consciously control like leg muscles for walking • Involuntary Muscle – muscles that function without conscious control like our organs – blood vessels, stomach, heart…

18. Transient Hypertrophy the muscle increases size from increased blood flow, temporary (30 min) and no strength gain

19. Chronic Hypertrophy – muscle gets larger and stronger from training

20. Muscle Atrophy – muscle shrinks from disuse

21. Muscle Injuries

22. Muscle Strain and TearsSymptoms: Pain, Weakness & Function

23. Muscle Strains/Tears

24. Treatment of muscle injury Rest – it takes time for the muscle to repair Ice – helps reduce the swelling and pain Compression – helps hold muscle in line and reduce the pain and swelling Return to action when function is no longer impaired. Returning too soon may result in re injury