itself consists of millions of nerve fibres which transmit electrical information to and
from the limbs, trunk and organs of the body, back to and from the brain. Nerves branch
out from the spinal cord through openings between the vertebrae. The brain and spinal
cord are referred to as the Central Nervous System, whilst the nerves connecting the
spinal cord to the rest of the body are referred to as the Peripheral Nervous System.
The spinal cord is connected to the brain and is about the diameter of a human finger.
From the brain the spinal cord descends down the middle of the back and is surrounded
and protected by the bony vertebral column. When the spinal cord reaches the lumbar
region, it splits into four bundled strands of nerve roots called the cauda equina
(meaning horsetail in Latin). The bundled strands on each side come together after
exiting from the spine to form one thick nerve bundle on each side called the sciatic
nerve.
Cauda equina and Sciatic nerveThe sciatic nerve exits from behind the pelvis and travels down the back of the thigh and
leg supplying the lower limb up to the toes. It is this nerve and its branches that get
compressed due to arthritis of the spine or herniation of the intervertebral disc. Pressure
or irritation of this bundle of nerves causes the characteristic pain called “sciatica”
which is felt in the buttocks and back of the thigh and leg. Additional compression can
cause tingling and numbness of the toes and even loss of movement of the toes.