In order, here are the things you have to know for the altas or poll evaluation.
1. The atlas is the YES joint, meaning it allows for extension and forward flexion of the neck (nose up and nose down). The complete YES joint is where the atlas meets with the base of the skull called the occiput.
2. The joint described above has two sides-right and left. But you wouldn't know that unless you saw this joint on a dry skeleton or in dissection and saw the two semi-round projections eminating from the base of the skull called "condyles." These two condyles fit in the atlas vetebra in the deep holes made for them called sulci (a sulcus on each side). When the atlas misaligns due to a muscle spasm, one of these sides of the atlas joint will become smaller--in other words, that side of the joint closes. A closed joint has less movement. It's as simple as that. But there is no way you can place your hand on top of the atlas (poll) and know this. You have to test the INSIDE of this joint, not the top of the vertebra. Here's how to do that.
3. Stand in front of your horse and grab each side of the halter close to the nose. While maintaining a frim grip, bend the horse's head to one side and scoot over with your feet while doing this. Then, raise the head straight up as high as it goes and remember how high the head went. Do the exact same thing for the other side. Remember, scoot over the exact distance on each side, otherwise you'll get a false positive. When you're done, ask yourself which side felt 'heavier' going up, right or left. Which side put up the most resistence? Right or left. The side that was harder to bring up to the same height is the side of the misaligned atlas and the muscle spasm. Why? Because you have to surmise it was more difficult to raise up due to a smaller joint--being closed by a muscle spasm. Do this test three times to make sure you get the same results each time. Side note: Sometimes you can get a false positive doing the YES test if the second neck bone (axis) is sore on one side. Where the second neck bone meets the atlas (first neck bone) is called the NO joint. And part of the test described above requires you to bend the horse's head to the right and left. If one side of the second neck bone is sore, then you won't be able to accurately access the first neck bone.
4. The move: Once you know the side of pain, stand on that side and follow these steps. Let's say the right side is sore.
Step one: Stand on the right side near the head. You and your horse are both facing the same direction.
Step two: With your left hand reach over the horse's head and grab the opposite atlas wing--in this case the left atlas wing. And hold that for firmly to stabilize it so it doesn't move during the adjusting. The atlas wing is big and it's the only big part of atlas (first neck bone) you can grab directly below the side of the skull--just behind the upper part of the jaw below the skull). It feels like a massive Frankenstein's bolt!
Step three: While squeezing the left atlas wing as just described, take your right hand and gradually push down on the horse's nose until the chin is fully tucked down towards the chest.
Step four: While your left hand is squeeing the left atlas wing, and your right hand is pushing down on the nose, rotate (push) the nose AWAY from you until it stops. This loads (stretches) the joint.
Step five: Once you've completed this step, maintaining the forward tuck and pushing away, then deliver a quick (not hard) impulse away from you--which is just a continuation or completion of the first push. Done.
Technically, this is not an atlas move since you're really not moving the atlas. What you're really doing is moving the head in relation to the atlas since you're keeping the atlas still by stabilizing it. Chiropractors call this an "occiput" (base of the skull) move.
As always, a short video clip is better than my explanations. Email me if you want a short, 20 second video clip emailed to you. firstname.lastname@example.org
Oh, I'm still looking for a barn to coduct a hands-on technique seminar very close to Corpus Christi, TX March 17th and 18th.
Dr. Daniel Kamen, D.C.