Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 1 Joseph E. Muscolino, DC Instructor, Purchase College State University of New York Owner, The Art and Science of Kinesiology Stamford, Connecticut KINESIOLOGY: The Skeletal System and Muscle Function Second Edition

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 2 Chapter 13: Roles of Muscles Joseph E. Muscolino, DC

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 3 Lesson 13.1 Objectives Define the key terms of this chapter and state the meanings of the word origins of this chapter. Describe the relationship between the role that a muscle plays and the action in question. Compare and contrast the roles of mover and antagonist. Discuss the concept of cocontraction.

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 4 Lesson 13.1 Objectives (cont’d.) State the muscle that is working during the action in question. Describe the relationship between gravity and joint actions. Explain the application of tight antagonists to restricted joint motion. Compare and contrast the roles of fixator and neutralizer.

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 5 Section 13.1—Mover Muscles Movers: muscles that can do the action in question Can shorten in two ways: –Concentrically contract and shorten –Relax and shorten For every joint action, a functional group of movers can contract to make the action happen.

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 6 Section 13.1—Mover Muscles (cont’d.) Most powerful mover = prime mover Other movers = assistant movers Movers are also known as agonists. Figure 13-1

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 7 Section 13.1—Mover Muscles (cont’d.) Figure 13-1

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 8 Section 13.2—Antagonist Muscles Antagonists do the opposite action of the action in question. Can lengthen in two ways: –Eccentrically contract and lengthen –Relax and lengthen Sometimes called contralateral muscle (opposite side)

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 9 Section 13.2—Antagonist Muscles (cont’d.) Most powerful antagonist = prime antagonist Figure 13-2

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 10 Section 13.2—Antagonist Muscles (cont’d.) Figure 13-2

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 11 Section 13.2—Antagonist Muscles (cont’d.) Contraction: when the agonist and antagonist contract at the same time –Not considered healthy –The same as pressing gas and brake pedals simultaneously

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 12 Section 13.3—Determining the “Muscle That Is Working” Muscle that is working = muscle that contracts during the action in question Easiest way is to examine gravity’s role in the action in question

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 13 Section 13.3—Determining the “Muscle That Is Working” (cont’d.) Three general rules: –Upward movements, movers work and antagonists relax –Horizontal movements, movers work and antagonists relax –Downward movements, antagonists work and movers relax

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 14 Section 13.3—Determining the “Muscle That Is Working” (cont’d.) Figure 13-3

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 15 Section 13.3—Determining the “Muscle That Is Working” (cont’d.) Figure 13-3

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 16 Section 13.4—Stopping Unwanted Actions of the “Muscle That Is Working” Fixators and neutralizers both stop unwanted actions of working muscle –Fixators stop action at fixed attachment –Neutralizers stop action at mobile attachment Example: flexion of the fingers into a fist

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 17 Lesson 13.2 Objectives Describe the general concept of the relationship between fixators and neutralizers and the muscle that is working. Give an example of a fixator and a neutralizer relative to a specific joint action. State the step-by-step method for determining fixators and neutralizers relative to a specific joint action.

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 18 Section 13.5—Fixator Muscles Fixators: stop unwanted action at the fixed attachment of muscle that is working Also known as stabilizers Contract isometrically Figure 13-4

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 19 Section 13.5—Fixator Muscles (cont’d.) Figure 13-4Figure 13-5

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 20 Section 13.5—Fixator Muscles (cont’d.) Figure 13-6 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 21 Section 13.6—Concept of Fixation and Core Stabilization Mobility (phasic) muscles: larger, longer, more superficial Postural stabilization (tonic) muscles: smaller, deeper, closer to joints Core stabilization, strength, and efficiency of movement Core stabilization and spinal health

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 22 Section 13.6—Concept of Fixation and Core Stabilization (cont’d.) Figure 13-7 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 23 Section 13.6—Concept of Fixation and Core Stabilization (cont’d.) Figure 13-8

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 24 Neutralizers stop unwanted action at the mobile attachment of the muscle that is working. –They create a contraction force equal in strength but opposite in direction to the force of the unwanted action. Section 13.7—Neutralizer Muscles

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 25 Section 13.7—Neutralizer Muscles (cont’d.) Figure 13-9

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 26 Section 13.7—Neutralizer Muscles (cont’d.) Figure 13-10Figure 13-11

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 27 Section 13.8—Step-by-Step Method for Determining Fixators and Neutralizers Determine the action in question. Determine the muscle that is working and its role. Determine the fixed and mobile attachments. List all actions of the muscle that is working, and state whether the actions are desired or undesired.

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 28 Determine the action of each fixator at the fixed attachment. Choose a muscle that can do the action determined for each fixator. Determine the action of each neutralizer at the mobile attachment. Choose a muscle that can do the action determined for each neutralizer. Section 13.8—Step-by-Step Method for Determining Fixators and Neutralizers (cont’d.)

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 29 Section 13.8—Step-by-Step Method for Determining Fixators and Neutralizers (cont’d.) Figure 13-12

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 30 Lesson 13.3 Objectives Describe the role of a support muscle. Explain the two ways in which a synergist can be defined. Compare and contrast synergists and antagonists for a given joint action. Explain the concept of coordination as it relates to the role of muscles. Describe the possible clinical effects of isometric contractions.

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 31 Lesson 13.3 Objectives (cont’d.) Define and give an example of a 2nd-order fixator. Explain why it is difficult to isolate a specific muscle contraction; further, explain and give an example of how muscle contractions tend to spread through the body. Discuss and give an example of the concept of coupled actions in the body.

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 32 Section 13.9—Support Muscles Hold another part of the body in position while the action in question is occurring Do not work directly at the joint Oppose the force of gravity on a body part Contract isometrically

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 33 Section 13.9—Support Muscles (cont’d.) Figure Figure 13-14

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 34 Section 13.10—Synergists Synergists: muscles or forces that work with the muscle that is contracting Example #1: Biceps brachii and pronator teres Figure 13-15

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 35 Section 13.10—Synergists (cont’d.) Example #2: Right external abdominal oblique and left internal abdominal oblique Figure 13-15

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 36 Section 13.11—Coordinating Muscle Roles Muscles rarely act in isolation. A number of muscles may contract for any given joint action. Coordination is the co-ordering of muscles in the body in their various roles to create smooth and efficient movement.

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 37 Section 13.11—Coordinating Muscle Roles (cont’d.) Clinical effects of isometric contractions –Close off veins for the entire length of contraction –Buildup of toxic waste products –Waste products irritate nerves

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 38 Section 13.11—Coordinating Muscle Roles (cont’d.) 2nd-order fixators –Fixators that fix attachments of fixator or neutralizer muscles Figure 13-16

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 39 Section 13.11—Coordinating Muscle Roles (cont’d.) Figure 13-17

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 40 Section 13.12—Coupled Actions Two separate joint actions that must occur simultaneously Figure 13-18