M43: Other deforming dorsopathies

M43.6: Torticollis

With this disorder, a muscle in the neck may have become shorter. When the muscle shortens it pulls your head over to that side. At the same time, your face turns slightly to your healthy side. You may be able to feel the contracted muscle as a thickening of the neck.

Another cause may be that your cervical spine is deformed or suffering from wear and tear. This can cause the neck to slant to one side.