I have a 14 year old cat. I stepped on her tail, why is her tail so sensitive?

I am a little confused by your question? Are you asking why it hurts when you step on it or why is it sensitive after your step on it? Regardless, the answer is really the same. All cats’ tails are sensitive and very susceptible to injury. The tail has several major components: skin, bone, blood vessels, nerves and subcutaneous tissue. When you step on the tail you are putting a lot of pressure on the bones and tissues of the tail. This can do some pretty severe damage. It would be like if someone stepped on your finger.