1. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Fundamentals of Anatomy & Physiology SIXTH EDITION Chapter 13, part 2 The Spinal Cord and Spinal Nerves

2. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Nerves consist of: Epineurium Perineurium Endoneurium 31 pairs of spinal nerves

3. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.8 A Peripheral Nerve Figure 13.8

4. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings White ramus (myelinated axons) Gray ramus (unmyelinated axons that innervate glands and smooth muscle) Dorsal ramus (sensory and motor innervation to the skin and muscles of the back) Ventral ramus (supplying ventrolateral body surface, body wall and limbs) Each pair of nerves monitors one dermatome Spinal nerves

5. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.9a Figure 13.9 Peripheral Distribution of Spinal Nerves

6. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.9b Figure 13.9 Peripheral Distribution of Spinal Nerves

7. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.10 Dermatomes Figure 13.10

8. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Complex interwoven network of nerves Four large plexuses Cervical plexus Brachial plexus Lumbar plexus Sacral plexus Nerve plexus

9. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.11 Figure 13.11 Peripheral Nerves and Nerve Plexus

10. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings SECTION 13-4 Principles of Functional Organization

11. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Sensory neurons Deliver information to CNS Motor neurons Distribute commands to peripheral effectors Interneurons Interpret information and coordinate responses General organization

12. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Functional group of interconnected neurons Neural circuit patterns Divergence Convergence Serial processing Parallel processing Reverberation Neuronal pools

13. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.15 Figure 13.15 The Organization of Neuronal Pools

14. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Reflexes are rapid automatic responses to stimuli Neural reflex involves sensory fibers to CNS and motor fibers to effectors An introduction to reflexes

15. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Wiring of a neural reflex Five steps Arrival of stimulus and activation of receptor Activation of sensory neuron Information processing Activation of motor neuron Response by effector Reflex arc

16. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.16 Components of a Reflex Arc Figure 13.16

17. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings According to development Site of information processing Nature of resulting motor response Complexity of neural circuit Reflex classification

18. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.17 Methods of Classifying Reflexes Figure 13.17

19. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Innate reflexes Result from connections that form between neurons during development Acquired reflexes Learned, and typically more complex reflex classifications

20. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Cranial reflexes Reflexes processed in the brain Spinal reflexes Interconnections and processing events occur in the spinal cord More reflex classifications

21. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Somatic reflexes Control skeletal muscle Visceral reflexes (autonomic reflexes) Control activities of other systems still more reflex classifications

22. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Monosynaptic reflex Sensory neuron synapses directly on a motor neuron Polysynaptic reflex At least one interneuron between sensory afferent and motor efferent Longer delay between stimulus and response and more reflex classifications

23. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.18 Neural Organization and Simple Reflexes Figure 13.18

24. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings SECTION 13-5 Spinal Reflexes

25. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Range from simple monosynaptic to complex polysynaptic and intersegmental Many segments interact to form complex response Spinal Reflexes

26. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Stretch reflex automatically monitors skeletal muscle length and tone Patellar (knee jerk) reflex Sensory receptors are muscle spindles Postural reflex maintains upright position Monosynaptic Reflexes

27. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.19 Components of the Stretch Reflex Figure 13.19

28. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.20 The Patellar Reflex Figure 13.20

29. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.21 Intrafusal Fibers Figure 13.21

30. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Produce more complicated responses Tendon reflex Withdrawal reflexes Flexor reflex Crossed extensor reflex Polysynaptic reflexes

31. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.22 The Flexor and Crossed Extensor Reflexes Figure 13.22

32. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Involve pools of interneurons Are intersegmental in distribution Involve reciprocal inhibition Have reverberating circuits to prolong the motor response Several reflexes may cooperate to produce a coordinated response Polysynaptic reflexes

33. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings SECTION 13-6 Integration and Control of Spinal Reflexes

34. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Brain can facilitate or inhibit motor patterns based in spinal cord Motor control involves a series of interacting levels Monosynaptic reflexes are the lowest level Brain centers that modulate or build on motor patterns are the highest Control of spinal reflexes

35. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Reinforcement = facilitation that enhances spinal reflexes Spinal reflexes can also be inhibited Babinski reflex replaced by planter reflex Reinforcement and inhibition

36. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.23 The Babinski Reflexes Figure 13.23

37. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings You should now be familiar with: The structure and functions of the spinal cord. The three meningeal layers that surround the CNS. The major components of a spinal nerve and their distribution in relation to their regions of innervation. The significance of neuronal pools. The steps in a neural reflex. How reflexes interact to produce complicated behaviors.