1. Anatomy and Physiology, Sixth Edition
Rod R. Seeley Idaho State University
Trent D. Stephens Idaho State University
Philip Tate Phoenix College
Chapter 12
Lecture Outline*
*See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Spinal Cord and Spinal Nerves
Chapter 12
Spinal Cord and Spinal Nerves

3. Spinal Cord Extends from foramen magnum to second lumbar vertebra
Segmented
Cervical
Thoracic
Lumbar
Sacral
Gives rise to 31 pairs of spinal nerves
Not uniform in diameter throughout length

4. Meninges Connective tissue membranes surrounding spinal cord and brain
Dura mater
Arachnoid mater
Pia mater
Spaces
Epidural: Anesthesia injected
Subdural: Serous fluid
Subarachnoid: CSF

5. Cross Section of Spinal Cord

6. Cross Section of Spinal Cord
Gray matter
Neuron cell cell bodies, dendrites, axons
Horns
Posterior (dorsal)
Anterior (ventral)
Lateral
Commissures
Gray: Central canal
White
White matter
Myelinated axons forming nerve tracts
Fissure and sulcus
Three columns or funiculi
Ventral
Dorsal
Lateral

7. Reflex Arc
Basic functional unit of nervous system and simplest portion capable of receiving stimulus and producing response
Components
Sensory receptor
Sensory neuron
Interneurons
Motor neuron
Effector organ

8. Stretch Reflex
Muscles contract in response to a stretching force applied to them

9. Golgi Tendon Reflex
Prevents contracting muscles from applying excessive tension to tendons

10. Withdrawal Reflex
Function is to remove a body limb or other part from a painful stimulus

11. Withdrawal Reflex with Reciprocal Innervation
Causes relaxation of extensors muscle when flexor muscles contract

12. Withdrawal Reflex with Crossed Extensor Reflex
When a withdrawal reflex is initiated in one lower limb, the crossed extensor reflex causes extension of opposite lower limb

13. Peripheral Nerves Consist of Axon bundles Schwann cells
Connective tissue
Endoneurium
Perineurium: Surrounds axon groups to form fascicles
Epineurium

14. Spinal Nerves

15. Dermatomal Map
Skin area supplied with sensory innervation by spinal nerves

16. Cervical Plexus C1-C4 Phrenic nerve
From C3-C5 cervical and brachial plexus
Innervate diaphragm

17. Brachial Plexus C5-T1 Major nerves Axillary Radial Musculocutaneous
Ulnar
Median

18. Axillary Nerve

19. Radial Nerve

20. Musculocutaneous Nerve

21. Ulnar Nerve

22. Median Nerve

23. Lumbosacral Plexus

24. Obturator Nerve

25. Femoral Nerve

26. Tibial Nerve

27. Fibular Nerve

28. PNS Disorders General disorders Infections
Anesthesia: Loss of sensation
Hyperesthesia: Increased sensitivity to pain, pressure, light
Paresthesia: Tingling, prickling, burning
Neuralgia: Nerve inflammation causing stabbing pain
Sciatica: Pain radiating down back of thigh and leg
Infections
Herpes: Skin lesions
Shingles or herpes zoster: Adult disease of chickenpox
Poliomyelitis: Infantile paralysis
Genetic and autoimmune disorders
Myasthenia gravis: Results in fatigue and muscular weakness due to inadequate ACh receptors