Human Anatomy and Histology · MU Plovdiv

77. Spinal cord – position, shape, size, segments. Roots of spinal nerves and spinal ganglion. Grey matter – arrangement and structure.

Inside: 16 sections · 18 labelled pictures · 30 flashcards · 10 min

Topic 77 of 138 in the MU Plovdiv syllabus for Human Anatomy and Histology (Dental Medicine, Year 2). The free AceMed note covers it in 16 sections, about 1,449 words (10 min of reading), with 30 flashcards.

In this note

  1. SPINAL CORD
  2. Enlargments:
  3. Exit of spinal nerves from the vertebral canal:
  4. External features:
  5. Segments:
  6. GRAY COLUMNS OF THE SPINAL CORD.
  7. Division:
  8. Lamina:
  9. WHITE SUBSTANCE
  10. Arrangment:
  11. Tracts:
  12. SPINAL NERVES
  13. Spinal Ganglia:
  14. Formation of spinal Nerves:
  15. 182 cont.
  16. Reflex Arch:

SPINAL CORD

  • Length: 45 cm, occupying the 2/3 of the vertebral canal.
  • Cylindrical in shape.
  • Begins: at the upper border of atlas vertebra as the continuation of the medulla oblongata, from foramen magnum.
  • Ends: at the level of L1-L2 in adults. In infant, it reaches the level of L3.
  • Its lower end called "conus medullaris" from the apex of conus medullaris a pia matter filaments "filum terminale" extends downwards to be attached to the back of the coccyx.

filled with cerebrospinal fluid.

Enlargments:

because there is more gray matter in the anterior grey horn "Particulary lateral region"

  • Have 2 enlargments:
  1. Cervical enlargment: giving the roots of the brachial plexus. (C5 - T1)
  2. Lumbar enlargment: giving the roots of the lumbar and sacral plexus. (L2-S3)

Exit of spinal nerves from the vertebral canal:

  • C1-C7: above the corresponding vertebra.
  • C8: below C7 vertebra.
  • T1-L5: below corresponding vertebra.
  • S1-S4: anterior and posterior sacral foramina.
  • S5 and Co: from the sacral hiatus.
  • So, the collection of nerves that will surround the filum terminale below the level of L2 vertebra resembling a horse tail is called "the cauda equina". It occupies the lower 1/3 of the vertebral canal and the whole sacral canal.
  • To calculate the vertebral level:
  • In cervical region: vertebral level = spinal segment – 1
  • In upper thoracic region (T1-T6): vertebral level = spinal segment – 2
  • In lower thoracic region (T7-T12): vertebral level = spinal segment – 3
  • In lumbar region: vertebral level = spinal segment – 4
  • All sacral segments + coccygeal segment are at the level of L1-L2 vertebra.

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