11_LectureOutline

11_LectureOutline - An Introduction to the Muscular System...

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An Introduction to the Muscular System 0. The Muscular System 0. Consists only of skeletal muscles 1. Muscle Organization and Function 1. Muscle organization affects power, range, and speed of muscle movement 2. Fascicles 0. Muscle cells ( fibers ) are organized in bundles ( fascicles ) Fascicle Arrangement 0. Classification of Skeletal Muscles 2. By the way fascicles are organized 3. By relationships of fascicles to tendons 4. Organization of Skeletal Muscle Fibers 3. Four patterns of fascicle organization 1. Parallel 2. Convergent 3. Pennate 4. Circular 5. Parallel Muscles 4. Fibers parallel to the long axis of muscle 5. For example, biceps brachii 6. Depends on total number of myofibrils 7. Directly relates to cross section of muscle 8. 1 in. 2 (6.45 cm 2 ) of cross section develops 50 lb (23 kg) of tension 1. Convergent Muscles 6. A broad area converges on attachment site (tendon, aponeurosis, or raphe ) 7. Muscle fibers pull in different directions, depending on stimulation 8. For example, pectoralis muscles 2. Pennate Muscles 9. Form an angle with the tendon 10. Do not move as far as parallel muscles 11. Contain more myofibrils than parallel muscles
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12. Develop more tension than parallel muscles 13. Unipennate 9. Fibers on one side of tendon 10. For example, extensor digitorum 14. Bipennate 11.Fibers on both sides of tendon 12. For example, rectus femoris 15. Multipennate 13.Tendon branches within muscle 14. For example, deltoid 3. Circular Muscles 16. Also called sphincters 17. Open and close to guard entrances of body 18. For example, orbicularis oris muscle of the mouth 4. Skeletal Motion 19. Skeletal muscles attach to skeleton, produce motion 20. Type of muscle attachment affects power, range, and speed of muscle movement Levers 21. Mechanically, each bone is a lever (a rigid, moving structure) 15.And each joint a fulcrum (a fixed point) 22. Muscles provide applied force (AF) 16.Required to overcome resistance (R) 23. Function of a lever is to change 17.Direction of an AF 18.Distance and speed of movement produced by an AF 19.Effective strength of an AF 24. The Three Classes of Levers 20.Depend on the relationship between applied force, fulcrum, and resistance 5. First class , second class , and third class 5. First-Class Lever 25. Seesaw or teeter-totter is an example 26. Center fulcrum between applied force and resistance 27. Force and resistance are balanced
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6. Second-Class Levers 28. Wheelbarrow is an example 29. Center resistance between applied force and fulcrum 30. A small force moves a large weight 31. Third-Class Levers 21.Most common levers in the body 22.Center applied force between resistance and fulcrum 23.Greater force moves smaller resistance 24.Maximizes speed and distance traveled Muscle Attachments to Other Tissues 7. Origins and Insertions 32. Muscles have one fixed point of attachment ( origin ) and one moving point of attachment ( insertion ) 33. Most muscles originate or insert on the skeleton 34. Origin is usually proximal to insertion
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This note was uploaded on 12/29/2011 for the course BIOLOGY 24011 taught by Professor Pan during the Fall '11 term at HCCS.

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11_LectureOutline - An Introduction to the Muscular System...

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