Your spine, or backbone, is a complex structure. It consists of more than 120 muscles, 220 individual ligaments, 100 joints and 33 individual vertebrae at birth, some of which fuse together as we grow older (for instance, our coccygeal vertebrae amalgamate to form our “tailbone”). Fun fact: We have the same number of vertebrae in our neck as a giraffe!
Put Your Back Into It
Between all the bony vertebrae, there’s just enough space for your rope-like spinal cord to slip through. If you assumed the spinal cord was thick and weighty, you were wrong: Once you’re four or five years old, it has usually reached about 16-20 inches long and 0.4-0.6 inches in diameter, at which point it stops growing—the rest of your body simply grows around it.
There have been huge leaps in medical technology in recent years for those who’ve suffered injury or other trauma to their backbones. One of the most promising areas of research is in stem-cell treatments, which have been shown to have restorative effects on damaged spinal cords. Researchers are also using cutting-edge electrical implants to reroute crucial brain signals to their correct destinations.
Shiver Me Timbers
Sometimes, when under stress, we feel an intense shiver up our spine. This is an instinctive reaction that stems from our more animalistic ancestors. When they were cold or frightened, their arrector pili muscles would instinctively cause the skin to contract and the hair to raise—something that manifests on modern humans as goosebumps—providing an extra layer of insulation and making the animal look bigger to scare off predators.