I know that in 4E D&D, there is a rule that states creatures are facing 360' at all times. I understand the nature of this when a creature occupies a square 'footprint' ex: 2x2, 4x4. But, when a creature (ex Horse) occupies 2x1 squares, and the rider of the horse is located as part of one of those squares, does the 360' facing still apply?
I am thinking that a rider, who occupies the 'head' section of a horse can not immediately spin his horse to threaten creatures that were previously unthreatened because the horse's "rump" section occupied the square between them.