What is the Spine

Human beings have an upright backbone which we call a spine, which is more precisely called the vertebral column.   From top to bottom, the spine has four sections: cervical, near the neck; thoracic, behind the rib cage; lumbar, behind the stomach; and pelvic, at the base of the spine, where the hips begin.  This column is straight when observed facing a person’s back, unless the person suffers a spinal pathology.  In a sideway view, however, the spine has a natural curvature, which develops in each individual, as the body grows and strengthens, from the fetal position in the womb, to the fully upright position as an adult.

Construction of the spine

The spine is composed of 33 individual vertebrae made of bone.  The upper 24 vertebrae are separated by a cartilage ‘cushion’ between them, called an intervertebral disk.  There are 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae in most humans.

The bottom nine vertebrae are fused together; five to form the sacrum, which is the center of the pelvic bone, and four to form the coccyx or tailbone.

Inside the solid column formed by these 33 bones, which fit one on top of the other, there is a canal which contains and protects the spinal cord.  The spinal cord is a thin string of nervous tissue and cells, about 17 or 18 inches long, which starts at the base of the brainstem, where our neck meets our skull.  As the spinal cord extends down, well protected inside this spinal canal, it serves as the ‘communicator’ to all the sensory and motor systems of the whole body.  We can move and feel because the spinal cord transmits messages called neural signals to the brain.  The brain, plus the bundle of nerves at the brainstem, and the spinal cord inside the spine, compose our central nervous system, which controls such crucial functions as our heartbeat, our breathing, our sensations, our consciousness, and our sleep.