What does "cross the reins" and "run down" mean with regard to horse racing?

Question

I'm familiar with many equine terms, but while reading the coverage about Big Brown, these terms have come up. What exactly does a jockey do when he/she "crosses the reins"? It's apparently a signal for the horse to run, but what are the mechanics of the action?

Big Brown "ran down" in the Preakness. Is that regarded as a fault, or is it commonplace? Is it an indicator of a conformation defect ? The only definition I could find said that it meant weak pasterns.

Answer 1

WHEN YOU RIDE

YOU HAVE YOUR REINS CROSSED NO ITS NOT A SIGNAL TO RUN ITS THE WAY WE HOLD THE REINS

Run downs are a bandage that help s the horse if if run's down on his back or front pasterns

we use a cut out type of soft cloth that sticks to the leg and then wrap with a very light and short bandage

He does NOT HAVE TO BE WEAK THERE

HE MIGHT JUST RUN DOWN A BIT BECAUSE OF THE SURFACE OF THE TRACK

A horse like him that does run HARD  might need them

again not all means he has a problem O.K.