APK 2100C Lecture Notes - Lecture 8: Agonist, Rectus Femoris Muscle, Skeletal Muscle
12 Jul 2016
School
Department
Course
Professor
Document Summary
Fascicles= bundles of fibers in skeletal muscle surrounded by perimysium arranged differently in various muscles longer fibers more range of motion. Circular fascicles in concentric rings found always around external body openings (sphincters) Origin broad fascicles converge toward tendon of insertion. Pennate short fascicles that attach obliquely to tendon running length of muscle. Parallel fascicles run parallel to long axis of muscle. First class arrangement is load-fulcrum-effort raises head off chest. Second class arrangement is fulcrum-load-effort stand on tip-toe . Muscle interactions if muscle crosses at a joint, it acts as that joint. Muscles that produce opposite actions lie on opposite sides of a joint. Agonist (prime mover)= contracts to cause action. Antagonist= stretches and yields to effects of agonist. Synergist= assists agonist add extra force reduce undesirable movements cancelling unwanted movements (make fist, muscles with multiple actions at joint) Fixators= fix bone in place (scapulae fixators in arm movements)
