Brunnstroms Clinical Kinesiology Sixth Edition CHAPTER 4 Muscle

Brunnstrom’s Clinical Kinesiology Sixth Edition Introduction § Discussion of muscles on a macroscopic level § Last chapter: physiology of motion § Present chapter: mechanics of motion § Presentation of both active and passive tissue influences on motion Copyright © 2012 F. A. Davis Company

Brunnstrom’s Clinical Kinesiology Sixth Edition Muscle Activity § Recording muscle activity § Electromyography § Electrodes—surface, needle, indwelling § Record contraction/relaxation patterns § Record relative amount of muscle activity Copyright © 2012 F. A. Davis Company

Brunnstrom’s Clinical Kinesiology Sixth Edition Muscle Activity § Muscle activation § § § Isometric

Brunnstrom’s Clinical Kinesiology Sixth Edition Muscle Activity—Anatomic § Muscle actions § Typical scenario: 1. Proximal attachment is stabilized. 2. Distal attachment moves toward proximal. 3. Distal segment moves against gravity. Copyright © 2012 F. A. Davis Company

Brunnstrom’s Clinical Kinesiology Sixth Edition Open (OKC) vs. Closed Kinetic Chain § OKC § § Distal segment free to move Uninfluenced by other segments or joints Non-weight-bearing CKC § § § Distal segment fixed Proximal and distal segments affected Weight-bearing Copyright © 2012 F. A. Davis Company

Brunnstrom’s Clinical Kinesiology Sixth Edition Muscle Activity—Anatomic § Reverse actions § Muscles sometimes have “reverse” actions: 1. Proximal attachments move toward distal attachments (closed kinematic chain [CKC]). 1. Such as flexion of the thigh at the knee while sitting down. 2. Eccentric actions are typical in reverse actions that go with gravity. Copyright © 2012 F. A. Davis Company

Brunnstrom’s Clinical Kinesiology Sixth Edition Muscle Activity—Functional § Agonist § Antagonist § Synergist Copyright

Brunnstrom’s Clinical Kinesiology Sixth Edition Muscle Strength § Muscle size § Cross-sectional area (CSA) § Larger CSA—greater force-generating capability § Hypertrophy § Atrophy Copyright © 2012 F. A. Davis Company

Brunnstrom’s Clinical Kinesiology Sixth Edition Muscle Strength § Fiber architecture § Fusiform § § Fascicles long and parallel Example: Sartorius Greater range of motion and speed capability Pennate (uni-, bi-, or multi-) § § Attach at oblique angles to a common tendon Greater force-producing capability Copyright © 2012 F. A. Davis Company

Brunnstrom’s Clinical Kinesiology Sixth Edition Muscle Strength § Length § Resting length § Crossbridge activity as a function of length § Length-tension relationship Copyright © 2012 F. A. Davis Company

Brunnstrom’s Clinical Kinesiology Sixth Edition Muscle Strength § Moment arm § 100% of muscle force rotates joint when insertion is perpendicular to bone segment § Example: elbow at 90°, biceps insertion § Angle of insertion influences torque Copyright © 2012 F. A. Davis Company

Brunnstrom’s Clinical Kinesiology Sixth Edition Muscle Strength § Active tension § Number of motor units § Type of muscle fibers (motor units) recruited § Rate (frequency) of firing of motor units Copyright © 2012 F. A. Davis Company

Brunnstrom’s Clinical Kinesiology Sixth Edition Muscle Strength § Age and gender § Increase in strength from birth to adolescence; peak between 20 and 30 years of age § Males generally stronger than females Copyright © 2012 F. A. Davis Company

Brunnstrom’s Clinical Kinesiology Sixth Edition Insufficiencies Applies only to multi-articulate muscles: Passive insufficiency § § § Can’t be stretched to full ROM at all joints simultaneously Active insufficiency § § Can’t contract to full ROM at all joints simultaneously Copyright © 2012 F. A. Davis Company