The spinal cord is well protected within the spinal canal inside the spine In adults, it measures approximately 42 cm for women and 45 cm for men And it is at the origin of all 31 pairs of spinal nerves The spinal cord, like the brain, is surrounded by the meninges membranes the pia mater, the arachnoid mater and the dura mater It’s surrounded by the CSF The CerebroSpinal Fluid and has a rudimentary hole in the center the central canal Because of intrauterine faster growth of the spine.
The nerve roots of the spinal nerves are offset relative to Intervertebral foramina they emerge from That is why the spinal cord ends at the level of the second lumbar vertebra although it gives nerves up to the fifth sacral vertebra and even the first coccyx vertebra The Lumbar puncture for collecting CSF is usually done below the second lumbar vertebra this prevents any injury to the spinal cord. The Spinal cord follows the path of the spine and draws two curvatures A Cervical with a posterior concavity lordosis and a dorsolumbar with anterior concavity kyphosis.
It also has two enlargements a cervical and a lumbar this is due to the innervation of the upper and the lower limbs. The Spinal cord ends down with the medullary cone that gives rise to the Cauda equina A cluster of lumbosacral nerve roots On a cross section, the spinal cord has a central region the gray matter which contains the neurons cell bodies and a peripheral part The white matter that consists of the axonal extensions and their myelin sheath The gray matter has the the shape of a butterfly.
With two anterior horns housing the motor neurons cell bodies and two posterior horns that receive sensory fibers At the thoracolumbar level, there are also lateral horns these hold the sympathetic fibers cell bodies The white matter is organized into three pairs of funiculi ventral, dorsal and lateral The spinal cord is marked by some grooves on its surface the deepest is the anterior median fissure the groove in the ventral side The posterior median sulcus is the groove in the dorsal side The spinal cord has also two lateral grooves on each side.