1. Chapter 16: The Bones and Soft Tissues

2. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 2 Function of the Skeletal System  Aids in movement  Supports and protects internal organs  Produces red and white blood cells  Stores minerals

3. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 3 Long Bone Anatomy  The structure of bones in the body allows them to be both lightweight and strong.

4. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 4 Structure of Long Bone  Cartilage  Red marrow  Spongy bone  Medullary cavity  Artery  Compact bone

5. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 5 Structure of Long Bone (cont.)  Endosteum  Yellow marrow  Periosteum

6. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 6 Fractures  Fractures are classified based on the various characteristics of the broken bone.

7. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 7 Fracture Types  Simple (closed) fracture: no skin penetration –Complete Two separate pieces Comminuted: three or more pieces

8. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 8 Fracture Types (cont.)  Simple (closed) fracture: no skin penetration –Incomplete Greenstick: in children with flexible bones Stress: due to overuse, weakness, biomechanical problems Epiphyseal plate: young people near growth plate

9. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 9 Fracture Types (cont.)  Compound (open) fracture: skin penetrated

10. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 10 Muscle Action  Most skeletal muscles work in groups to accomplish a smooth, coordinated action.

11. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 11 Moving the Skeleton  Prime mover: A muscle that is a major contributor to a particular movement, such as the biceps brachii for arm flexion. (The strong brachialis muscle could also be considered a prime mover of arm flexion.)

12. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 12 Moving the Skeleton (cont.)  Antagonist: A muscle that is a major contributor to the opposite movement of a prime mover, such as the triceps brachii (which causes arm extension).

13. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 13 Moving the Skeleton (cont.)  Synergists: Muscles that work together with a prime mover to help it produce a smooth, steady movement, such as the brachioradialis helping the biceps brachii during arm flexion.

14. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 14 Moving the Skeleton (cont.)  The role of a particular muscle (prime mover, antagonist, synergist) will likely change for different skeletal joint movements.  For example, the biceps brachii is a prime mover for arm flexion, but it is an antagonist for arm extension, for which the triceps brachii is the prime mover.

15. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 15 Muscle Stimulation  Muscles are controlled by stimulation from neurons of the nervous system.

16. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 16 Control of Contraction  The signal to contract a muscle begins with neurons in the brain or spinal cord, which communicate with other neurons that ultimately reach the neuromuscular junction.

17. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 17 Control of Contraction (cont.)  Dendrites carry signals toward the cell body, and the axon (one per neuron) carries signals away from the cell body toward other neurons, muscles, or glands.

18. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 18 Control of Contraction (cont.)  Though there is only one axon per neuron, most axons branch at some point and can stimulate several other neurons or muscle cells at the same time.  Many axons, but not all, are surrounded by insulating Schwann cells, which also allow for faster transmission of the nerve signal.

19. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 19 The Nerve Impulse  The normal, resting nerve cell (neuron) maintains an unequal distribution of electrical charge from the inside (negative) of the cell to the outside (positive).

20. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 20 The Nerve Impulse (cont.)  A nerve impulse is a change in the neuron’s membrane, due to a series of ion movements, that makes the outside negative and the inside positive.

21. Copyright ©2004 by Thomson Delmar Learning. ALL RIGHTS RESERVED. 21 The Nerve Impulse (cont.)  When the impulse passes (it can travel the complete length of the neuron), the membrane returns to its normal resting state. In other words, it repolarizes.