SPINAL CORD

Dr. Saeed Shafi

Objectives

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

5th Month

At Birth

3rd month

Parts of the spinal cord

• Conus medularis

• Cauda equina

• Filum terminale

• Lumbar subarachnoid cistern

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

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

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)

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)