Several years ago I audited a symposium with Ellen Bontje, an Olympic rider and trainer from Holland. Here are the links to my blogs about it:
Ellen Bontje's Symposium. Training and First level
Ellen Bontje's Symposium. Second and Third level
Ellen Bontje's Symposium. Fourth level and Prix St. George
Ellen Bontje's Symposium. Grand Prix

Working with the riders Ellen Bontje reminded them often to pay attention to the horse's neck - how straight it is, how long, the quality of stretch (a horse reaching for the bit elongating the neck, or, a horse pushing up against the bit contracting his neck back into the whithers), the shape of the neck (roundness starts from the base up and out), quality of the contact (elastically reaching to the bit). Sometimes Ellen would simply say to a rider: Ride the Neck!

At the time I didn't take it as seriously as I should have. Lately I have been paying more attention to all these things Ellen was talking about during the symposium. It started to become more clear how important it is not only to ride a horse forward to the bit but also the path to the bit which includes the neck most flexible part of the horse's body hence easiest to manifest resistances, crookedness and lack of balance and connection. Recently, I had a few light bulb moments which had everything to do with controlling the horse's neck.

• Imagine you are suspending his neck between the reins, think of his neck as an arched bridge that connects whithers to the bit
• Imagine you are slightly flexing your horse left and right at the same time (not back and forth)
• You are always looking for positive stretch into the bit initiated by a horse
• You are always looking for even contact no matter the movement or direction
• Inside rein is as important as outside rein. Balance them!
• Never push any rein into horse's neck! (a light bulb moment for me!)
• Outside rein leads a horse into leg-yield and shoulder-in
• Outside rein asks the horse to collect in travers, half-passes and pirouettes (provided the horse is lifting to it from inside leg)
• To have straightening/collecting effect outside rein half-halt must have a quality of an opening rein, rein that prepares to lead into a new direction even if it is not going to happen that was my biggest bulb moment that changed so many things!

When your horse resists the contact by tightening the neck upward think of dropping the neck down rather then simply resisting back or even worse pulling backwards. For example, you have asked your horse for medium trot and he flattened and hurried a bit and pressed his neck upward feeling hard in the reins. Do not brace and pull the horse to slow down. Stay supple in your seat focusing on the tempo and swing you want, ask your horse to drop his neck and THEN come with the leg/s. Way more likely your horse's response be more positive and correct. How you ask to drop his neck can be quite specific to your horse but in principle take time and look for small changes rather than big yanks and pulls. As Ellen said - Ride the Neck!

Happy riding...