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Spinal Cord

Spinal Cord. A. Spinal cord anatomy 1. Protection and coverings a. Vertebral column b. Meninges 2. External anatomy of the spinal cord 3. Internal anatomy of the spinal cord B. Spinal cord physiology 1. Reflexes

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Spinal Cord

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  1. Spinal Cord • A. Spinal cord anatomy 1. Protection and coverings a. Vertebral column b. Meninges 2. External anatomy of the spinal cord 3. Internal anatomy of the spinal cord • B. Spinal cord physiology 1. Reflexes 2. Reflex arc and homeostasis a. Physiology of the stretch reflex b. Physiology of the flexor (withdrawal) reflex and crossed extensor reflexes • C. Spinal nerves 1. Composition and coverings 2. Distribution of spinal nerves 3. Dermatomes

  2. The Spinal Cord • 1. is continuous with brain • 2. mediates spinal reflexes • 3. is site for integration • 4. provides the pathways

  3. Protection and Coverings • 1. vertebral canal • 2. meninges • 3. cerebrospinal fluid

  4. Meninges and Spaces • 1. epidural space • 2. dura mater • 3. subdural space • 4. arachnoid membrane • 5. subarachnoid space • 6. pia mater -- denticulate ligaments

  5. External Anatomy • 1. cylindrical • 2. flattened A-P • 3. foramen magnum to L2 • 4. differential growth • 5. cervical enlargement • 6. lumbar enlargement • 7. conus medullaris • 8. filum terminale • 9. cauda equina • 10. functional segments

  6. GROSS ANATOMY OF THE SPINAL CORD

  7. Internal Anatomy • 1. gray matter • 2. white matter • 3. gray commissure • 4. central canal • 1. gray matter • 2. white matter • 3. gray commissure • 4. central canal

  8. Gray Matter • 1. nuclei • 2. horns a. dorsal -- sensory b. ventral -- motor c. lateral -- autonomic

  9. Spinal Nerve Roots • 1. dorsal root (axons of sensory neurons) -- dorsal root ganglion (cell bodies of sensory neurons) • 2. ventral root (axons of motor neurons) Dorsal roots Dorsal root ganglion Ventral roots

  10. White Matter • 1. columns a. anterior b. posterior c. lateral • 2. tracts a. ascending b. descending Posterior columns Lateral columns Lateral columns Anterior columns

  11. Tracts of the Spinal Cord

  12. Terminology Review

  13. The Spinal Cord Has Two Essential Functions • 1. convey impulses between the periphery and the brain • 2. provide integrating centers for spinal reflexes

  14. Reflexes are… • 1. inborn • 2. unlearned • 3. unconscious

  15. Somatic Reflexes Versus Visceral Reflexes • Somatic reflexes involve the somatic nervous system. • Visceral reflexes involve the autonomic nervous system.

  16. Reflex Arc 3 2 4 5 4 5 2 1 3 • 1. receptor • 2. sensory neuron • 3. integration center • 4. motor neuron • 5. effector sensory receptor sensory receptor center of integration with association neuron center of integration with association neuron sensory (afferent) neuron sensory (afferent) neuron motor (efferent) neuron motor (efferent) neuron effector effector

  17. THE REFLEX ARC AS A FEEDBACK SYSTEM CONTROLLED CONDITION A stimulus or stress disrupts membrane homeostasis by altering some controlled condition RETURN TO HOMEOSTASIS The action of the effector returns the body process to within its normal homeostatic range RECEPTOR The receptors in a reflex are sensory neurons associated with a receptor device (transducer) and which relay nerve impulses to a central control center EFFECTORS The motor neurons initiate some response by an effector (muscle or gland) to counteract the stimulus that originally disrupted homeostasis CONTROL CENTER The control center is an integrating center of neurons in the CNS. It relays the information to motor neurons

  18. Reflex arc

  19. Stretch Reflex • 1. monosynaptic • 2. muscle spindle • 3. muscle tone • 4. ipsilateral • 5. reciprocal innervation

  20. The Flexor and Crossed Extensor Reflex Intersegmental Polysynaptic Ipsilateral Pain receptor Role of association neurons Reciprocal innervation Intersegmental Polysynaptic Contralateral Pain receptor Role of association neurons Reciprocal innervation excitatory neurons inhibitory neurons

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