Dr . Nirajan Neupane

Spinal cord & spinal nerves

Spinal cord (Myelon)

• 45 cm in length

• Continuation of medulla oblongata through Foramen magnum

and ends as conus medullaris at the level of lower border of L1 vertebra( in infant L3)Inside vertebral canal/ spinal canal/ neural canal of vertebral column

• Covered by spinal meninges (PAD) subarachnoid space : CSF

• Cavity of spinal cord is called central canal / neurocoel lined by

ependymal cells(surrounded by gray commissure)filled with CSF

Spinal nerves

• 1 pair from one spinal segment and come out of vertebral column through intervertebral foramen

• Mixed nerve

• C8T12L5S5Co1 = 31 pairs

• C1-7 above respective vertebrae , C8 below C7 vertebra, T1 to Co1 ,

below respective vertebrae

• Collection of spinal nerve root ( lumbar , sacral & coccygeal) below conus medullaris around filum terminals is cauda equina

• C8T12L7S4Co6 = 37 pairs (Rabbit)

• No. Of spinal nerves in frog = 10 pairs