What motions do horses ears make and why?

Horses have extremely mobile ears - they can move in almost any direction. Horses in the wild use their ears to help detect predators, and even though domestic horses don't need to do that, they still use their ears to tune into the environment around them, so generally, wherever their ears are pointed, that's what they're paying attention to - so if they're keeping an ear on you, that's a sign that they're paying attention to what you're doing! In addition, horses use their ears to express feelings. A happy, alert horse will have his ears pointed forward. An upset horse will have them about halfway back, and a frightened or angry horse will pin them back so they're almost flat against his head.