Why a cavesson?
Until about a year ago I thought a cavesson was just a fancy piece of equipment that unless you were German or did upper level dressage, you didn't need. Now I recommend them to nearly every client I meet. This is a simplified example of the mechanics at play when we use a cavesson (leading from the top of the nose) vs. a halter (leading from the bottom of the chin). Because the point of contact is different, these two methods affect the horse's head and neck in different ways. And as we know, everything is connected and this affects the rest of the body too.
The rope halter doesn't allow as much innate healthy lateral flexion, because of where we are applying the pressure. The chin and nose come first, and the opposing action of that halter is that it's actually pushing the rest of the head away from you. If you're aware, you can feel this immediately. If the horse is rotating the poll away from us, like in the halter photo, we haven't set them up very well to be able to rotate that poll in the direction of the bend, which is our goal most of the time. The horse has already lost it's balance and we haven't even gone anywhere yet.
The cavesson, by contrast, helps keep the head in better vertical alignment as we apply contact. The ears stay level, and the horse is able to rotate the poll in the direction of the bend. This has implications at the base of the skull, throughout the cervical vertebrae and of course through to the hind legs as well.
I don't mind rope halters, I use them in situations when I think it's appropriate. But if you're doing in-hand work, lunging, asking for bend, or otherwise conditioning your horse, consider how a cavesson might be a more supportive piece of equipment!