The spinal cord extends the entire length of the vertebral canal at 3 months of development. By birth it reaches L3 and in adults it reaches L1. The dura and arachnoid extend to S2 in adults. The spinal cord has a conus medullaris, cauda equina, and filum terminale. During development, the lumen of the neural tube becomes the ventricular system and central canal of the spinal cord. The gray matter forms from the alar and basal plates separated by the sulcus limitans. The white matter develops from axons myelinating within the spinal cord.

1. SPINAL CORD
Dr. Saeed Shafi

2. Objectives

8. Positional changes of spinal cord
• Uptil 3rd
month, the spinal cord extends the
whole length of vertebral canal
• At 6 month it lies at level of S1
• At birth – at level L3
• In adult – at level L1
• The dura & arachnoid extends up to S2 in
the adults. However, piamatter finishes at
the apex of conus medularis and then
continues as filum terminale

9. 5th
Month

10. At Birth

11. 3rd
month

13. Parts of the spinal cord
• Conus medularis
• Cauda equina
• Filum terminale
• Lumbar subarachnoid cistern

14. • Formation of:-
– ventral medial fissure
– Dorsal median sulcus
– Sulcus limitans

16. Lumen of neural tube
• Cavity of neural tube develops into
ventricular system of CNS
– Two lateral ventricles in cerebral hemispheres
– 3rd
ventricle in diencephalon
– 4th
ventricle behind brain stem
– Central canal of spinal cord
– Aquiduct of midbrain

17. Gray matter of spinal cord
• It is derived from differential growth of
mental zone of neural tube results in
formation of
– Alar plate (dorsal gray horn)
– Basal plate (ventral and lateral gray horn)
– Roof plate (posteriorly)
– Floor plate (anteriorly)
– Sulcus limitanse (separating alar and basal
plates)

20. White matter of spinal cord
• It is derived from growth of axons from
mental zone of spinal cord, brain and
neurons (of neural crest origin) in dorsal
root ganglia. Later on these axons are
myelinated resulting in formation of white
matter of spinal cord (white matter)