A cat's tail is more than just a furry appendange. Even though it's not technically part of the spinal cord, a cat's tail has 19 to 23 vertebrae, about 10 percent of the total number of bones in the animal's body. A labyrinth of muscles, ligaments, and tendons helps the kitty to strut, chase, communicate, and balance. Nerves extend from a cat's spinal cord into the tail, and are connected to the hind legs, bladder, large intestine, and anus. Yanking on a cat's tail can stretch or even tear the nerves, causing pain and possibly affecting the animal's ability to walk.
A tale of two kitties: