Centre of Excellence: Spine

The spine plays a crucial role in the body’s movements and capabilities. The spine is not made up of many bones. Instead, it is an intricate network of nerves that transports millions of impulses between the body and the brain. In addition to giving strength and stability to stand, bones provide the purpose of protection. They guard the spine in the same way that the ribs guard the heart and the skull guards the brain. Since people started using their legs to walk, the mechanics of the spine have undergone a number of appropriate changes. Animals have horizontal spines. Walking on two legs for specific purposes resulted in chimpanzee and then humans being fully bipedal as a result of evolution.

The spine has to go through a number of structural and functional changes during the metamorphosis process. Some animals developed the ability to stand up from a horizontal position by walking with bent knees and hips. Humans developed straight hips and knees to support their upright stance. The spine was changed with the appropriate curvature as compensation. The human spine reaches all the way from the neck to the bottom. Despite being in a straight line, it has several curves from front to rear. The cervical and thoracic regions of the spine can be broadly separated. sacrum, lumbar, and coccyx (bottom region), all of the abdomen. The animals’ previously existing tails progressively regressed into a little remnant known as the Coccyx (tail bone).

In the neck the first two bones got modified to support the head called atlas and axis. The bones of the spine are called vertebrae, which has a thick part called body in the front, pedicles in the middle that has supporting joints and a ring to host the spinal cord called lamina and the final projecting part backwards is the spinous process. Each part has a distinct function. The body is strong that gives stability to stand, pedicles have the joints that holds all the bones in alignment and the joints provide the mobility, the bony ring protects spinal cord, and finally the spinous process holds the spinal muscles on the back.

The intervening discs and the surrounding strong muscles facilitates mobility as well as stability. The ligaments in front, back, around the spinal joints decides the range of movements at each level. These movements vary from part to part having maximum movement at the neck followed by the lumbar region. There are 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 5 coccygeal bones. The sacral and coccygeal ones are united together as a single piece that supports the pelvic structures.

In reality disc between the two vertebral bodies acts like a washer and shock absorber facilitating the movements. All these structures are prone to wear and tear causing degeneration over the time which in turn disturbs the nerve function. When the disc becomes dry it can crack and the inner jelly like structure will come out pressing the nerves causing severe pain. So it is essential to maintain the integrity of all these structures by regular exercises, proper posture, training of supportive muscles and avoiding damage to those sensitive structures.

Though there are lot of checks and balances to prevent damage, inadvertently one can injure any of them leading to either temporary or permanent damage causing pain and difficulty in movement. The spinal nerves exit at different levels to supply various parts of the body (motor nerves), while the counterparts provide feedback (sensory nerves) to the brain respectively. In addition, fibres from the autonomic nervous system (sympathetic and parasympathetic) that control lungs, heart, blood vessels, gut, bladder and sexual organs are also located within. Thus, spinal cord is essentially a large cable containing millions of delicate fibbers that provides bidirectional connections between the brain and individual parts of the body. The blood supply to this entire cable is very critical as its ability to endure insults of any kind is poor even comparison to brain.

References:

Venkatramna, N. (2022). The Human Spine, Brain Voice, Vol.3(11): 4-5.

Article by— Dr. Faiz Bux

Asst. Prof., Department of Botany

Kalinga University, Chhattisgarh

faiz.bux@kalingauniversity.ac.in