Anatomy Bones and Muscles · MU Pleven

124. Spinal cord – form, position, envelopes and blood supply.

Covers the length, position and shape of the spinal cord, where it begins and ends in adults and infants, and the filum terminale and conus medullaris. Explains the cervical and lumbar enlargements with their nerve roots, the cauda equina, and where each spinal nerve exits the canal. Includes a segment count and a formula for converting spinal segment to vertebral level.

Inside: 5 sections · 4 labelled pictures · 20 flashcards · 2 min

Topic 123 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 5 sections, about 283 words (2 min of reading), with 20 flashcards.

In this note

  1. SPINAL CORD
  2. Enlargements:
  3. Exit of spinal nerves from the vertebral canal:
  4. External features:
  5. Segments:

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.

Enlargements:

  • Have 2 enlargements: because there is more gray matter in the anterior grey horn "Particularly lateral region"
  1. 1) Cervical enlargement: giving the roots of the brachial plexus. (C5-T1)
  2. 2) Lumbar enlargement: 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.

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