1. Muscle

2. What are muscles? n Machines –purpose of machines is to help us do work.

3. Characteristics of Muscle Tissue n Extensibility n Elasticity n Contractility n Irritability n Amplitude n Viscosity

4. What is a muscle contraction?

5. Types of Contractions n Concentric Contraction n Static Contraction n Eccentric Contraction n Isometric and Isotonic Contractions

6. Concentric Contractions n development of tension within a muscle with consequent shortening of the muscle. n the movement is caused by the muscle.

7. Static Contraction n development of tension within a muscle with no change in the overall muscle length. n goal is usually to maintain a position.

8. Eccentric Contraction n development of tension within a muscle resulting in lengthening of the muscle. n movement is caused by another force n contracting muscle tries to control the movement.

9. Mechanical Factors determining specific movements n structure of the joint or joints muscle crosses n the orientation of the muscle’s line of pull to the axis or axes around which movement is permitted

10. Line of Pull n the direct line between the centers of the muscle’s attachments n one origin, one insertion n one origin, multiple insertions

11. Mechanical Axis n the straight line drawn connecting the centers of the joints at each end of the specific bone, or n from the center of the joint where the movement is occurring to the center of the distal end of the limb, if the limb is moving as a unit

12. Axis of Rotation n the angle formed by the line of pull and the mechanical axis.

13. Muscle Roles n Individual muscles take on a variety of roles at different times and under different circumstances. n there are six roles a muscle can assume

14. Muscles and their Roles n Muscles are not selective when stimulated to contract. n Resulting actions are partially determined by functions performed by other muscles attendant to the agonist.

15. Muscle Roles n Agonist n Antagonist n Fixator n Regulator n Neutralizer n Synergist

16. Agonist n Prime Mover n causes a concentric contraction

17. Antagonist n refers to a muscle whose function is opposite to that of some muscle tending to cause a movement. n Three different functions: –relax throughout the movement –relax initially, but contract toward the end of the movement to prevent injury –contract throughout the movement

18. Fixator n any muscle that contracts to anchor or steady the position of a particular bone n Two categories of fixators: –Stabilizing role - –Supporting role -

19. Regulator n used to identify a muscle contracting eccentrically to control a movement caused by an external force.

20. Neutralizer n acts to prevent the undesired action of another contracting muscle without interfering with the desired function of that other muscle n two types –mutual neutralizer - –true neutralizer -

21. Synergist n usually assigned to the synchronous action of two joint muscles n 2 types –Concurrent pattern - –Countercurrent pattern -

22. Control of Movement n Coordination is an orchestrated sequencing of binary impulses n Reciprocal Innervation (Sherrington’s Principle) –inhibition of one member of antagonistic pair n Corollary –inhibition of muscle is inhibited

23. Conditions for Co-contraction n when an exact amount of tension or accurate placement of a limb is needed n deceleration of limb n to stabilize the wrist for precise hand movements or for a powerful grip

24. Ballistic Movements n Three phases: –Acceleration- –Inertial- –Deceleration-

25. Ballistic Movements n muscle initially contracts to move the limb, but then the limb is carried through space due to momentum n antagonistic muscles fire to slow down the speeding limb

26. Stretch Reflex n occurs in skilled ballistic movements n muscle is stretched quickly, resulting in a stronger contraction

27. Olson’s Principles n Dealt with free weights only and considered: –direction of movement relative to the line of gravity –the type of contraction –the muscle group used

28. Olson’s 1st Principle n If the movement is against the line of gravity: –the muscle causes the movement –the contraction is concentric –the muscle group that should perform the action, performs the action

29. Olson’s 2nd Principle n If the movement is through the line of gravity: –the muscle causes the movement –the contraction is concentric –the muscle group that should perform the action, performs the action

30. Olson’s 3rd Principle n If the movement is toward the line of gravity: –the resistance causes the movement –the contraction is eccentric –the muscle group that is opposite to the joint movement acts to control the movement

31. Ulibarri’s Corollaries to Olson’s Principles n These corollaries restate Olson’s Principles relative to the: –direction of the weight (resistive force) –type of muscle contraction –muscle group used

32. Ulibarri’s 1st Corollary n If the weight (resistive force) moves against the line of gravity: –the muscular force causes the movement –the contraction is concentric –the muscle group that should do the action, performs the action

33. Ulibarri’s 2nd Corollary n If the weight (resistive force) moves toward the line of gravity: –the resistive force causes the movement –the contraction is eccentric –the muscle group that is opposite to the joint action acts to control the movement