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Types of Muscles Introduction to Chapter 10

Types of Muscles Introduction to Chapter 10. Opposites!. For every movable joint in the body, there are two opposing muscle groups: the agonist, which moves the segment of the body in one direction and the antagonist, which moves it in the opposite direction. . Types of Muscles.

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Types of Muscles Introduction to Chapter 10

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  1. Types of MusclesIntroduction to Chapter 10

  2. Opposites! • For every movable joint in the body, there are two opposing muscle groups: the agonist, which moves the segment of the body in one direction and the antagonist, which moves it in the opposite direction.

  3. Types of Muscles • Biceps and the Triceps muscles have opposing effects, one flexing and the other extending the arm • Agonist or Prime mover – major muscle responsible for a particular movement – bicep brachii • Antagonist – reverses the direction of the prime mover – tricep brachii • Are always found in pairs! • http://sciweb.hfcc.net/biology/ap/233/233lecture/muscles.myology/anat/movements/agonist.antag.html

  4. Types of Muscles • Synergists – help the prime movers by producing the same action or reducing undesirable movements. Helps with stabilization. • Ex. Brachialis lateral and below the biceps brachii

  5. More types • Fixators – specialized synergists that hold a bone still or stabilize the origin of the prime mover. All the tension helps move the insertion bone. • EX. Postural muscles of vertebrae and muscles that anchor the scapula to the thorax

  6. Muscles • Prime movers, antagonists, synergists and fixators all must work in concert to permit smooth movement of the skeleton

  7. Origin can be found where the muscle attaches to a bone directly The insertion can be found where the muscle tapers into tendon or aponeurosis and the aponeurosis inserts itself to a different bone Origin vs. Insertion

  8. Origins • May be one, two, three or four muscle origins

  9. Important!! • Most muscles span joints and are attached in two places • When the muscle contracts the movable bone, the muscle’s insertion moves towards the muscle’s origin on the immovable bone.

  10. Direct attachments – epimysium fuses directly to the periosteum of bone or to cartilage Indirect attachments – by tendon or aponeurosis Can cross bony areas without being shredded like muscles would Usually a bursa sac is directly underneath the indirect attachments Types of Attachments

  11. Direct vs. Indirect

  12. An aponeurosis is a long, flat tendon Fascia consist of sheets of fibroareolar tissue (superficial) or dense, inelastic connective tissue (deep fascia) Deep fascia is what forms the epimysium, perimysium and endomysium Tendons are densely packed collagen fibers

  13. Naming Muscles • http://training.seer.cancer.gov/anatomy/muscular/groups/ • Size, shape, fiber direction, location, number of origins, origin and insertion and action (adductor, abductor, flexor, extensor, levator, masseter)

  14. Circular Convergent Multipennate Parallel Unipennate, Fusiform Bipennate Go to page 327 and identify which muscles in the body have this arrangement. ***Of the muscles illustrated, which would shorten most? Which two are probably most powerful and WHY! Arrangement of Fasicles

  15. Lever Systems; Bones and Muscles Lever – rigid bar that moves on a fixed point or fulcrum, when force is applied to the bar. Effort = applied force Load = resistance http://www.fi.edu/pieces/knox/automaton/lever.htm

  16. Or fulcrum Or fulcrum

  17. Mechanical Advantage Mechanical Advantage = when a lever allows a given effort to move a load farther and faster. Power lever = a lever that has a mechanical advantage Example: Car jack – more work for less effort

  18. Mechanical Disadvantage If the load is far from the fulcrum, more effort is required and more force is required by the muscle. Mechanical disadvantage levers operate as speed levers. This is exemplified by carrying a load of dirt with a shovel.

  19. First Degree Lever • fulcrum lies between the effort and the load

  20. Second Degree Lever • load lies between the fulcrum and the effort

  21. Third Degree Lever • effort lies between the fulcrum and the load

  22. Identify the levers! • Go to http://www.dynamicscience.com.au/tester/solutions/hydraulicus/humanbody.htm and answer the questions using the information from the previous slides. • Make sure your group comes to a consensus!

  23. Question? • What three elements modify muscle activity? Go to page 330 for the answer!

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