Structure

The spinal cord is a symmetrical reflex organ, i.e. divided into two similar halves (=bilateral) and, in contrast to the brain, has a relatively original and simple structure, which in principle looks the same in its various sections. Analogous to the spinal column, it can be divided into the breech or coccygeal marrow, which is still present in other vertebrates, is rudimentary in humans, i.e. only the functionless system is still present. From the spinal cord, pairs of nerve roots, the spinal nerves (Nervi spinalales), extend symmetrically to the left and right.

These nerve roots run evenly on each side through the intervertebral holes (Foramen intervertebralis), which are formed by two superimposed vertebrae on the right and left of the vertebral bodies. In this short section they are called spinal nerve roots (Radix spinalis), because they still consist of a front (motor = for the muscles) and a rear (sensitive = for the sensation) part.

Cervical or cervical marrow (at the level of the 1st -7th cervical vertebra)
Thoracic or thoracic marrow (at the level of the 1st -12th thoracic vertebrae)
Lumbar or lumbar mark (at the level of the 1st – 5th lumbar vertebra)
Cross or sacral medulla (at the level of the sacrum)
Transverse process
Outgoing nerve (spinal nerve)
Vertebral body
Spinous process
Spinal cord

Only after leaving the intervertebral holes do the two root parts unite to form the actual spinal nerve, which moves to the periphery of the body.Thus the spinal root is both the control center for two fundamentally different qualities and for two different directions of conduction: perceived input from the outside is directed from the periphery to the central nervous system (spinal cord and brain) – and at the same time, calls for movement from the central nervous system to the muscles, to the periphery. The two qualities (motor and sensory parts) are naturally retained in the nerve, they are simply no longer distinguishable from each other and run as a common “cable”. Since they are electrically isolated by the fatty nerve sheaths (myelin sheaths), they do not get in each other’s way.