The definition of asinine is to be silly, stupid or ridiculous. An example of asinine is a foolish prank played on a friend.
In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical and lumbar vertebrae; they increase in size going towards the lumbar vertebrae, with the lower ones being a lot larger than the upper.
I think you meant vertebrae not vertebrates. Human body usually has 33 vertebrae, but that number can vary.