This questioned was posed on a bulletin board. The OP had recently been diagnosed with abnormal curvature in her cervical vertebrae and it brought to mind for her how the horse’s neck might be affected by a rider working against the horse. Rolkur anyone?
Jrga responded to the question and graciously agreed to have it brought over here for further discussion. Here is the response:
There is no optimal position of the neck, as it is meant to be flexible and move in different ways to accomplish different things for the horse in nature.
That being said, just as in a human, there are positions it was never meant to hold for any length of time. What is always optimal is that the vast majority of time that the neck is not in any forced position, and that it is ‘stretched’ appropriately to the task at hand.
Mechanically, different neck vertebra are shaped differently, and trying to force movement that is limited by the bone structure will cause catastrophic injuries. The first vertebra is to move up a tiny fraction, and down when released from muscle tension, it is meant to move right or left, ie, flexion at the poll. Note, it is to move right or left, not break down or back to any great degree or to rotate, flexion is not primarily about engaging the first vertebra but releasing it. The second vertebra is the swivel, useful to a horse, not something we wish to engage as riders, ie, to cause head tilt. The infamous third vertebra and the ones behind it can give up and down movement as well as side to side movement. Since the third vertebra bends down by engaging muscles, many pulled upon horses (too much rein, tie downs, martingales used improperly, break the neck at the third vertebra incorrectly.
If we engage the vertebra enough in ways that they aren’t meant to be engaged, use tie downs and leverage devices to force a shape, then the muscles and ligaments tend to tighten accordingly, reinforcing poor positioning of the vertebra and causing chronic ‘tightness’ and pain, etc.
Deb Bennett gave a lecture at the George Morris clinic this year on biomechanics, and she demonstrated with a skull and neck bones, there are few better demonstrations on how necks work. If they are still there, it would be worth going over the the US Equestrian site and hunting through the video links for those lectures, they are free of charge.
Basically, the combine system of neck bones and muscles work correctly, ie, optimal for horses generally, when the appropriate muscles are engage to stretch the neck out of its resting S curve shape to a flatter shape, which shape actually starts to arch as it stretches to its fullest extent. As the stretch becomes more pronounced and the curves behind the poll and at the base of the neck flatten, the top line (nuchal ligament and muscles) stretch and relax. This produces the greatest flexibilty and strength for the neck, relaxed muscles don’t tear, they move easily. A by product is that the short muscles around the poll release allowing the nose to drop towards vertical. The end result is the base of the neck is raised, flattening the horse’s spine from shoulder to rump as much as possible within the limits of the horse’s conformation, and the neck arches, poll approaches the highest point, there is a hollow gullet below the neck and the nose drops towards the vertical. Raising the back, arching the neck through stretching the top line, is one of the most important aspects of collecting a horse. The single and foremost step is engagement of the hindquarters at the SI, ie, engaging the musculature of the power center to lift its side of the back as well as bring the rear legs under the horse, relaxing the neck so that the base of the neck may raise and the S curve stretch and flatten out, is the second step.
If you pull the nose in, the horse will generally tighten the base of the neck, using the large muscle under the neck, drop the base of the skeletal structure,increasing any tendency to be down hill that already exists in the horse, and hollow the back and make it impossible for collection to occur. The front legs are also affected negatively by this, they can’t swing freely, and the horse drags itself along with its front feet, tightening chest muscles, losing flexibility for lateral work, and stressing tendons and ligaments meant to stabilize the leg by forcing them to function in place of the big butt and thigh muscles in the rear that were meant for locomotion.
No horse was meant to have its neck all arched up in collection all the time, nor pulled back by restrainig hand or devices, if you want to take the do no harm position, long and level is good, but it doesn’t help a horse to counteract the weight of a rider nor exhibit particularly athletic movement.
First link is a skeleton drawing that show the upper and lower curves, an Arab would probably have a more pronounced and longer upper curve in the S, the much desired mitbah that contributes to their swan neck look, an ewe necked horse would have a lower and deeper and longer part to the lower S curve, which is why they bulge out in the under neck and tend to stargaze:
The second link is a skeletal drawing where the neck has stretched, forming an arch and spine is made level (not all horses will be level even with properly engaging the neck, it depends on how downhill or uphill their conformation is:
Relaxed long and low:
A horse carrying its neck this way is going to be hammer-headed, note there is no turnover at the upper S curve, the spine meets the head like the handle of the hammer meets the head of a hammer:
Relaxed long and low in a real horse, but also note that the rider still hasn’t fully released the neck and note the reflection along the top line, it drops at the withers, by holding the nose too much, the base of the neck has dropped too much given that the horse is in long and low, this is not yet optimal:
A horse similar to the hammer headed look, dropping in the base of the neck, also notice how short the neck looks, it isn’t stretched, this horse looks ‘ewe necked’ but I don’t think in his case it is a natural part of his conformation but a result of how he is typically handled, either way, ths is far from optimal:
This looks like an actual long low base of the neck, honest to goodness ewe neck to me, YMMV, whoever posted the picture captioned it as such, as well:
A nicely built neck, showing long and straight stretch, follow the reflection of light along the top line, ignore the crest, and see that it does not drop from the withers, there is a gullet below (base of neck raised) and a fairly smooth column of muscle at mid neck, showing even without the horse being engaged, note honest flexion, nose to inside but not tilted or nose held in in any way:
Fully stretched and arched neck (on a horse with ‘baroque characteristics”, ie, heavy and muscular with a deep neck, broad back and large haunch, note this is levade not rear, a highly collected movement, hindquarter engaged, neck stretched and handler’s head is in the way, but the nose would actually be slightly in front of the vertical:
This is just ugly, a beautifully built neck being abused for no reason, and won’t create collection, this is pulling that is so beyond not optimal:
I haven’t shown you a nicely optimal neck in a highly collected ridden horse yet, I’m still looking, which is kind of sad. There are some out there, but you have to kiss a lot of frogs first.
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