Humans are born with 33 separate vertebrae. By adulthood, we typically have 24 due to the fusion of the vertebrae in the sacrum.
The top 7 vertebrae that form the neck are called the cervical spine and are labeled C1-C7. The seven vertebrae of the cervical spine are responsible for the normal function and mobility of the neck. They also protect the spinal cord, nerves and arteries that extend from the brain to the rest of the body.
The upper back, or thoracic spine, has 12 vertebrae, labeled T1-T12.
The lower back, or lumbar spine, has 5 vertebrae, labeled L1-L5. The lumbar spine bears the most weight relative to other regions of the spine, which makes it a common source of back pain.
The sacrum (S1) and coccyx (tailbone) are made up of 9 vertebrae that are fused together to form a solid, bony unit.
and i find the basis of rotation, i.e. the boulder of mysterious power, lies in t1, on which the arm-shoulder triangle clings to and is generated to make a 3d rotating-ascending-descending, up-and-down like hitting motion, which might be as well the most difficult part of golf motion to comprehend and operate. (but please just imagine the myth delta to move on a simple 2d vertical plain. not the entire delta, but only a segment with its centre of gravity and t1 as both ends is 'grooved' within the plain vertical to the ground to exploit out the most contrifugal force along with gravity. and this is the mysterious power i've been always talking about!
When viewed from the front or back, the normal spine is in a straight line, with each vertebra sitting directly on top of the other. Curvature to one side or the other indicates a condition called scoliosis.
When viewed from the side, the normal spine has three gradual curves:
The neck has a lordotic curve, meaning that it curves inward.
The thoracic spine has a kyphotic curve, meaning it curves outward.
The lumbar spine also has a lordotic curve.
These curves help the spine to support the load of the head and upper body, and maintain balance in the upright position. Excessive curvature, however, may result in spinal imbalance.
All of the elements of the spinal column and vertebrae serve the purpose of protecting the spinal cord, which provides communication to the brain, mobility and sensation in the body through the complex interaction of bones, ligaments and muscle structures of the back and the nerves that surround it.
The true spinal cord ends at approximately the L1 level, where it divides into the many different nerve roots that travel to the lower body and legs. This collection of nerve roots is called the cauda equina, which means “horse’s tail,” and describes the continuation of the nerve roots at the end of the spinal cord.
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