Question

how the spinal cord is working

Answer 1

Spinal cord is a part of Central nervous system which connects brain to nerve roots, which supplies the effector organs and , receive connections from nerve roots of periphery to rely them to brain. They also form a part of the reflex arc, where an inter-neuron in spinal cord will form a connection between the afferent and efferent neurons.
spinal cord can be compared to the cable connection between the rely station(brain) and the cables(nerve roots) of our home.

There are 33 spinal cord nerve segments in a human spinal cord:
8 cervical segments forming 8 pairs of cervical nerves,
12 thoracic segments forming 12 pairs of thoracic nerves,
5 lumbar segments forming 5 pairs of lumbar nerves 5 (or 1) sacral segments forming 5 pairs of sacral nerves,
3 coccygeal segments joined up becoming a single segment forming 1 pair of coccygeal nerves.

The spinal cord is made from part of the neural tube during development.The spinal cord is supplied with blood by three arteries that run along its length starting in the brain, and many arteries that approach it through the sides of the spinal column.
The three longitudinal arteries are called the anterior spinal artery, and the right and left posterior spinal arteries

Afferent spinal pathways:
Somatosensory organization is divided into the dorsal column-medial lemniscus tract (the touch/proprioception/vibration sensory pathway) and the anterolateral spinothalamic system, or ALS (the pain/temperature sensory pathway). Both sensory pathways use three different neurons to get information from sensory receptors at the periphery to the cerebral cortex. Proprioceptive information in the body travels up the spinal cord via three tracts.

Efferent spinal pathways:
The corticospinal tract serves as the motor pathway for upper motor neuronal signals coming from the cerebral cortex and from primitive brainstem motor nuclei.The midbrain nuclei include four motor tracts that send upper motor neuronal axons down the spinal cord to lower motor neurons. These are the rubrospinal tract, the vestibulospinal tract, the tectospinal tract and the reticulospinal tract. The rubrospinal tract descends with the lateral corticospinal tract, and the remaining three descend with the anterior corticospinal tract.
source : http://en.wikipedia.org/wiki/Spinal_cord