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Articulatio atlantooccipitalis et atlantoaxialis
Yes and no are two different joints — and the short muscles beneath measure more than they pull.
Also known as: atlas · C1 · axis · C2 · first cervical vertebra · second cervical vertebra · dens · odontoid · upper cervical spine · head joints · atlanto-occipital · atlanto-axial · occiput
Open in the tool — with search and all the links →This compilation is for information and replaces neither medical diagnosis nor treatment. If you have symptoms, see a doctor.
Between the skull and the spine sit two joints built differently from all the others. The atlas, the first cervical vertebra, has no vertebral body — it is a ring on which the skull rests like a bowl on two joint surfaces. The second vertebra, the axis, carries an upward peg, the dens, and around this peg the atlas and skull rotate. That gives a clean division of labour: nodding — the yes — happens between skull and atlas, turning — the no — between atlas and axis. About half of all head rotation takes place in this one joint, some forty degrees to each side out of eighty to ninety. The rest is spread over the five vertebrae below. Between skull and atlas and between atlas and axis there is no disc; the first disc of the spine sits only between the second and third cervical vertebra. What holds the dens in place are ligaments — above all a transverse band that presses it like a belt against the front arch of the atlas, and two short alar ligaments to the occiput, which at the same time limit rotation. Through the transverse processes of both vertebrae the vertebral artery runs on each side to the brain; above the atlas it makes a pronounced loop so that it can follow the rotation. Striking too is the musculature immediately under the occiput: these short muscles have one of the highest densities of muscle spindles in the whole body — sensors that continuously report to the brain how the head sits in space. They measure more than they pull.
First the chin slowly to the chest and back — that is the upper joint. Then turn the head without taking the shoulders along — that is the lower one. If only one of the two directions feels tight, that says more than a general “the neck is stiff”.
Bringing the chin to the chest and then turning largely switches off the vertebrae below — what rotation remains comes almost only from the joint between atlas and axis. A simple way to feel the difference between top and bottom yourself.
Because these muscles mainly measure, they respond poorly to strong pulling and well to small, slow, frequent movements. Moving the head to its limit in all directions a few times a day and pausing briefly there does more here than one long stretch in the evening.
Head and eyes are closely coupled: leading with the eyes first and letting the head follow often goes further and with less tension than turning alone. Conversely the neck stays stiff when the gaze is fixed on one point — which is why screen work loads the neck more than the same time spent walking.
A neck that turns poorly is everyday life. It is different if, after an accident, a fall on the head or a violent jolt, neck pain comes with numbness, weakness in arms or legs, swallowing trouble, double vision or severe dizziness. Neck pain that feels completely unlike anything before also deserves assessment rather than treatment. In inflammatory joint diseases and in Down syndrome the ligament holding the dens can be looser — worth knowing before any vigorous treatment at the neck.
About 40 to 45 degrees of rotation to each side come from the atlas–axis joint, with 80 to 90 degrees usual in total. Nodding between skull and atlas covers some 15 to 20 degrees. A restriction after a harmless cause usually improves within days to two weeks. If it stays unchanged beyond four to six weeks, an examination is worthwhile — not out of danger, but because something other than a passing irritation is then usually behind it.
Low values over a long time cause a dull ache in bones and trunk-near muscles and a morning stiffness that eases with movement. At the neck this is regularly blamed on posture.
A swaying feeling that comes and goes with head position is often blamed on the neck. More often positional vertigo is behind it: it spins hard, lasts seconds to a minute and is triggered by lying down or turning in bed — not by holding the head. The difference matters, because one is fixed with a simple manoeuvre and the other with movement.
Only to rule out. A restriction of the head joints does not raise inflammatory markers. Fever, neck stiffness and feeling ill together are something else and must be looked at at once.
In long-standing rheumatoid arthritis the ligament holding the dens can give way. This has become rare since the disease is treated earlier — before any vigorous manual treatment at the neck it is still the first question to ask.
Not for the joint but for the bone underneath. Before a treatment working with pressure or thrust on the spine, bone density is the real question — not the method.
The bone under the joint, not the joint itself. At the neck this matters especially because the load-bearing structure is slim: the atlas is a ring a few millimetres thick.
The short neck muscles work all day without a break — they hold the head, even when sitting. With tension in exactly this area magnesium is the first thing asked about; the studies are mixed, the mechanism at the muscle fibre is not.
Only if tingling, numbness or unsteady walking in the dark comes with the stiff neck. A deficiency causes the same sensations as a compressed nerve in the neck — and is therefore often blamed on the cervical spine.
Most often taken for neck tension. Human studies vary; anyone trying it notices within two to four weeks whether anything changes. Over longer periods, soft stool is the usual limit on the amount.
For the bone, not for the joint. Before any treatment working with pressure or thrust on the upper cervical spine, bone density is the real question.
Clearly worthwhile and well supported when deficient — vegan, older adults, certain drugs. No energy boost without a deficiency.
The neck is where tension settles first — and the short muscles under the occiput are the first to join in. That is why a headache coming from the neck increases under strain and often disappears by itself on holiday.
The mobility of the head joints depends on movement, posture and tension, not on food. What counts on the plate concerns the bone underneath and the muscles — and over years, not weeks.