This is just another reminder how weird a centaur is as a concept. Vertebrates don't have more than 4 limbs. Land vertebrates mostly have 4 legs, but the structure of their forelegs is very similar to human arms and wrists. Bats have wings, but their wings are basically arms with a membrane of skin between the bones. Even a Naga (human / snake hybrid) makes more sense than a centaur.
Also, think how unbalanced a centaur would be. Instead of a trunk that merely has to support a neck and a head, a centaur has to support a full half-human right at the front of its body. That would shift the centre of mass way forward, so most of the weight would be on the middle limbs. That would affect its ability to gallop, because in a gallop most of the running power of a horse comes from the back legs. If the back legs are almost completely unloaded because all the weight is at the front, the back legs wouldn't be able to push with much force.
A more realistic centaur would have the trunk weight shifted backwards, so instead of having a human torso replacing its neck and head, it would be like a rider on a horse but without the rider's legs or the horse's head.
