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Anatomy and Physiology, Sixth Edition

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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

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