The 24-year-old, who will be out of contract at the Broadfield Stadium in January, has made just three appearances for Crawley this season.
"I have told [Henderson] he does not figure in my plans at the moment and I want to give him as much opportunity as possible to get himself sorted out. We hope it works out well for him up in Scotland," manager Mark Yates told the club's official website.
Henderson started his career with Arsenal, for whom he made one senior appearance during a FA Cup tie against Leyton Orient.
Since then he has had spells with Coventry City, Hull City and Stevenage.