As it comes out I was operating on a pretty fundamental misunderstanding of what a jaw flexion is in dressage terms. You see, I was told at one point in time that a jaw flexion was a slight rotation of the head to the left or right. In classical dressage, it appears, "jaw flexion" is just another way of saying "mouthing the bit."
My last post on jaw flexions brought up Philippe Karl, a person I decided I needed to do some research on. So I went to the library and got a copy of "Twisted Truths of Modern Dressage." WOW, what an interesting book. According to French classical dressage, horses that brace their necks (like Coriander) and have a hard time taking up contact (like Coriander) are often clamping their mouth shut. If you can get them to relax their jaws (by mouthing the bit), the poll, neck, shoulders, and back will follow in due course.
"Since the horse's mouth receives the action of the hand, it is the mouth that the rider must persuade and have yield from the outset. The horse displays its agreement to talk with the hand by softly mobilizing its tongue and lower jaw. When the horse "tastes" its bit in this way, this allows the rider to ask for variations in attitudes in the following order: lateral neck flexions, extension of the neck and poll flexion."
-Philippe Karl, "Twisted Truths of Modern Dressage"
Interested, I decided to dig a bit deeper and went to the source: Francois Baucher's "New Method of Horsemanship" (free for Kindle).
"The head and neck of the horse are at once the rudder and compass of the rider. By them he directs the animal; by them, also, he can judge the regularity and precision of his movements. The equilibrium of the whole body is perfect, its lightness complete, when the head and neck remain of themselves easy, pliable and graceful. On the contrary, there can be no elegance, no ease of the whole, when these two parts are stiff. Preceding the body of the horse in all its impulsions, they ought to give warning, and show by their attitude the positions to be taken, and the movements to be executed. The rider has no power so long as they remain contracted and rebellious; he disposes of the animal at will, when once they are flexible and easily handled. If the head and neck do not first commence the changes of direction, if in circular movements they are not inclined in a curved line, in backing they do not bend back upon themselves, and if their lightness is not always in harmony with the different paces at which we wish to go, the horse will be free to execute these movements or not, since he will remain master of the employment of his own forces.
From the time I first noticed the powerful influence that the stiffness of the neck exercises on the whole mechanism of the horse, I attentively sought the means to remedy it. The resistances to the hand are always either sideways, upward or downward. I at first considered the neck alone as the source of these resistances, and exercised myself in suppling the animal by flexions, repeated in every direction. The result was immense; but, although the supplings of the neck rendered me perfectly master of the forces of the fore-parts of the horse, I still felt a slight resistance which I could not at first account for. At last I discovered that it proceeded from the jaw. The flexibility I had communicated to the neck even aided this stiffness of the muscles of the lower jaw, by permitting the horse in certain cases to escape the action of the bit. I then bethought me of the means of combating these resistances in this, their last stronghold; and, from that time, it is there I always commence my work of suppling.
The importance of these flexions of the jaw is easily understood. The result of them is to prepare the horse to yield instantly to the lightest pressure of the bit, and to supple directly the muscles that join the head to the neck. As the head ought to precede and determine the different attitudes of the neck, it is indispensable that the latter part is always in subjection to the other... That would be only partially the case with the flexibility of the neck alone, which would then make the head obey it, by drawing it along in its movements. You see, then, why at first I experienced resistances, in spite of the pliability of the neck, of which I could not imagine the cause. The followers of my method to whom I have not yet had an opportunity of making known the new means just explained, will learn with pleasure that this process not only brings the flexibility of the neck to a greater degree of perfection, but saves much time in finishing the suppling. The exercise of the jaw, while fashioning the mouth and head, brings along with it the flexion of the neck, and accelerates getting the horse in hand."
-Francois Baucher, "New Method of Horsemanship"
It appears that I've stumbled into the major discrepancy between classical dressage and modern, competition dressage. I imagine modern dressage looks at this method and exclaims, "They are riding the horse from front to back, heresy!"
But is it? Is it really? When modern dressage relies on contraptions like the crank noseband to keep the horse's mouth shut- by people who claim to ride "from back to front."
When horses are literally coating their chests in foam because their parotid glands are being squeezed empty from the hyperflexion of the neck- by people who claim to ride "from back to front."
Which method do you think the horse would choose?
Glenshee Equestrian Center has a post on jaw flexions too. Check it out.