1 / 42

The Role of Muscles

The Role of Muscles . Applied Kinesiology 420:151. Agenda. Introduction to muscles Attachments Structural classification Types of muscle action Factors affecting muscle function Coordination of muscles Types of movements. Introduction to Muscles. Movement occurs via: Internal force

ciaran-guy
Download Presentation

The Role of Muscles

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Role of Muscles Applied Kinesiology 420:151

  2. Agenda • Introduction to muscles • Attachments • Structural classification • Types of muscle action • Factors affecting muscle function • Coordination of muscles • Types of movements

  3. Introduction to Muscles • Movement occurs via: • Internal force • External force. Examples?

  4. Introduction to Muscles • Properties of skeletal muscle: • Extensibility • 50% increase • Tendons too • Contractility • 50% decrease • Only muscle • Elasticity • Tendons too • Irritability

  5. Agenda • Introduction to muscles • Attachments • Structural classification • Types of muscle action • Factors affecting muscle function • Coordination of muscles • Types of movements

  6. Attachments • How does skeletal muscle attach to bones? • Directly? • Connective tissue coverings (tendon) • Tendons: • Round cord, flat band, aponeurosis • Embedded within bone

  7. Attachments • Origin and insertion • Tendon length • Stability/mobility tendency • Proximal/distal tendency • Proximal and distal attachment • Less error • Example (arm curl vs chin-up)

  8. Attachments • More terms • Extremities: Proximal and distal • Diaphragm: Peripheral and central • Head/Neck/Trunk: • Vertical lines of pull: Upper and lower • Horizontal lines of pull: Medial and lateral

  9. Agenda • Introduction to muscles • Attachments • Structural classification • Types of muscle action • Factors affecting muscle function • Coordination of muscles • Types of movements

  10. Structural Classification • Fiber arrangement • Longitudinal • Quadrate • Triangular (radiate) • Fusiform • Unipenniform • Bipenniform • Multipenniform

  11. Longitudinal • Structure: • Long • Strap-like • Consistent diameter • Examples: • Sartorius • Rectus abdominis Figure 8.7

  12. Quadrate • Structure: • Four-sided • Usually flat • Examples: • Pronator quadratus • Rhomboid Figure 3.3

  13. Triangular (Radiate) • Structure: • Fibers radiate from narrow to broad attachment • Examples: • Pectoralis major • Gluteus medius Figure 3.3

  14. Fusiform • Structure: • Rounded • Tapered endings • Examples: • Biceps brachii • Brachialis Figure 3.3

  15. Unipenniform • Pennate  Feather • Structure: • Series of short parallel fibers • Feather-like arrangement from side of tendon • Examples: • Extensor digitorum longus • Tibialis posterior Figure 3.3

  16. Bipenniform • Structure: • Similar to unipenniform • Two sets of fibers • Examples: • Flexor hallucis • Rectus femoris Figure 3.3

  17. Multipenniform • Structure: • Similar to bipenniform • Multiple tendons • Examples: • Middle deltoid Marieb & Mallet, 2001, Figure 11.3

  18. Effect of Fiber Arrangement on Force Output • Concept #1: Force directly related to cross-sectional area  more fibers • Example: Thick vs. thin longitudinal/fusiform muscle? • Example: Thick fusiform/longitudinal vs. thick bipenniform muscle? • Concept #2: As degree of pennation increases, so does # of fibers per CSA

  19. Agenda • Introduction to muscles • Attachments • Structural classification • Types of muscle action • Factors affecting muscle function • Coordination of muscles • Types of movements

  20. Types of Muscle Action • Contraction vs. action • Concentric • Internal > external = + work • Eccentric • External > internal = - work • Isometric • Internal = external = 0 work • Isotonic • Is this really possible? • Isokinetic

  21. Agenda • Introduction to muscles • Attachments • Structural classification • Types of muscle action • Factors affecting muscle function • Coordination of muscles • Types of movements

  22. Factors Affecting Muscle Function • Line of pull • Angle of attachment • Length-tension relationship • Force-velocity relationship • Stored elastic capabilities

  23. Line of Pull • The direction of any movement caused by a muscle is due to: • #1: Joint structure • Example: Elbow flexion (biceps brachii) vs. knee extension (rectus femoris) • #2: The relation of the line of pull to the joint • Example: Upper fibers pectoralis major as abductor/adductor

  24. The location of the line of pull in relation to the joint center determines the movement in this case Figure 3.4

  25. Angle of Attachment • The angle of attachment affects the efficiency of the movement • Internal forces have two components • Rotary force • Parallel force • Stabilizing • Dislocating Parallel forces do not cause movement therefore reduce efficiency

  26. Perpendicular No Parallel Force Stabilizing or dislocating? Maximum efficiency Hamill & Knutzen, 2004, Figure 3.23

  27. Stabilizing or dislocating? More or less? Hamill & Knutzen, 2004, Figure 3.23

  28. Length-Tension Relationship • Optimal length rule  Slightly longer than maximum resting length • Too short  no force  why? • Too long  no force  why?

  29. Active + Passive Optimal? Active Too long? Too short? Passive Figure 3.7

  30. Force-Velocity Relationship • Concentric actions • Inversely related • Vmax = F0  vice-versa • Why? Cross-bridges take time • Eccentric actions • Directly related until . . .

  31. Figure 3.8

  32. Stored Elastic Capabilities • Rapid stretch  concentric action = more work • Why? Stored elastic energy • As speed increases so does effect • Up to a certain point • Addition of stretch reflex  SSC

  33. Agenda • Introduction to muscles • Attachments • Structural classification • Types of muscle action • Factors affecting muscle function • Coordination of muscles • Types of movements

  34. Coordination of Muscles • Role of muscles • Biarticular muscles

  35. Role of Muscles • Agonists • Directly responsible for movement • Synergists • Stabilizers • Neutralizers • Antagonists • Reciprocal inhibition • Braking

  36. Synergists as Stabilizers Support of limb  Deltoid example Figure 3.9

  37. Synergists as Neutralizers Pectoralis minor and serratus anterior

  38. Biarticular Muscles • Proximal/distal attachments cross 2 joints • Not long enough for full ROM • Result? Tension of one biarticular muscle transferred to opposite muscle • Example: Hamstrings and rectus femoris • Advantage over monoarticular muscles? Concurrent Movement

  39. Biarticular Muscles • Concurrent vs. countercurrent movements • Maximum ROM • Passive/active insufficiency

  40. Agenda • Introduction to muscles • Attachments • Structural classification • Types of muscle action • Factors affecting muscle function • Coordination of muscles • Types of movements

  41. Types of Movements • Passive • Example: Partner stretch or falling to ground • Active: • Slow  Constant force = inefficient • Rapid  Ballistic = efficient • How to stop ballistic movement • Antagonist • Passive resistance of connective tissue and eccentric action • External object

  42. Review • The muscle fiber (pp. 46-48) • Fast vs. slow twitch (pp. 48)

More Related