why are there an irregularity in the amount of vertebrae humans have?

Question

im studying a yoga course at the moment and one of my assignment questions it asks me to answer the following;
"The vertebral column usualy consists of 33 vertebrea.sometimes 34. which part of the vertebral column is responsible for this inconsistancy?" please help me out! thankyou4ur time. maryemtester

Answer 1

Consider the coccyx (link 1).

This is the lowest part of the spine, and usually consists of four vertebrae. Variations have been noted, however, of an extra or missing vertebra at that point. Most medical sources list the number of human vertebrae as being between 32 and 34, therefore.

Of course, most people have more than that - they just aren't usually born with them. Analysis of embryos between four and five weeks of age reveals a tail with 10-12 developing vertebrae inside it (link 2). Most of us re-absorb such features, however, and even though some people are born with what seems to be a tail (link 3), I don't think they usually contain even one vertebra.

Answer 2

The very bottom of the spine, the sacrum and coccyx, consists of vertebrae that are separate originally, but fuse before birth.