Anatomy and Function of the Spinal Cord Mod 1 Part 1

Sep 8, 2024

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Chapter 13: Spinal Cord and Spinal Nerves

Overview

  • Introduction to the basic anatomy and function of the spinal cord and spinal nerves.
  • Exploration of central nervous system (CNS) components: brain and spinal cord.
  • Focus on spinal reflexes and pathways.

Spinal Cord Anatomy

  • Starting Point: Foramen magnum of the skull.
  • Cervical Enlargement: In lower cervical and upper thoracic vertebrae; associated with brachial plexus.
  • Lumbar Enlargement: Associated with the lumbar plexus; increased neural traffic to the legs.
  • Conus Medullaris: End of the spinal cord around L1 to L2.
  • Cauda Equina: Bundle of nerves extending from L3 to S5 and coccygeal nerve.

Meningeal Layers

  • Pia Mater: Innermost layer, shrink-wraps the CNS.
  • Arachnoid Mater: Contains and circulates cerebrospinal fluid in the subarachnoid space.
  • Dura Mater: Tough outer layer; forms dural sheath.
  • Epidural Space: Contains adipose tissue for cushioning.

Stabilization Structures

  • Denticulate Ligaments: Stabilize the spinal cord laterally.
  • Filum Terminale: Extends from the conus medullaris, providing vertical stabilization.

Gray Matter vs White Matter

  • Gray Matter: Interior, organized into horns.
  • White Matter: Exterior, organized into columns for vertical information transfer.
  • Bilateral Symmetry: Spinal cord has left/right symmetry.

Dorsal and Ventral Roots

  • Dorsal Root: Sensory, incoming information; contains dorsal root ganglion.
  • Ventral Root: Motor, outgoing information.

Spinal Cord Pathways

Ascending Tracts (Sensory)

  • Spinothalamic Pathway:
    • Anterior tract: Crude touch and pressure sensations.
    • Lateral tract: Pain and temperature.
    • Dicussation occurs shortly after spinal entry, contralateral ascension.
  • Posterior Column Pathway:
    • Carries fine touch, vibration, pressure, and proprioception.
    • Does not synapse immediately, a sends ipsilaterally.
  • Spinocerebellar Pathway:
    • Carries proprioception directly to cerebellum.
    • Anterior and posterior tracts, distinct ipsilateral ascension.
    • Unique double decussation in the anterior pathway.

Spinal Cord Structures in Lab

  • Nerve Anatomy: Similar to muscle, with layers like epineurium, perineurium, and endoneurium.
  • Sympathetic Chain: Communicating rami link to sympathetic ganglion.

Upcoming Topics

  • Descending Pathways: Motor commands from brain to body.
  • Spinal Reflexes: Mono- and polysynaptic reflexes.

These detailed notes summarize the key topics covered in the lecture on the spinal cord and its components, providing a comprehensive review of the anatomical and physiological aspects for future study and reference.