Apparatus for testing and/or exercising the rotary neck muscles which are used to twist or turn the neck from side-to-side about a generally vertical pivot axis passing through the cervical vertebrae. The head is held by and between a pair of pads mounted on a rotatable frame fixed to a movement arm...http://www.google.sh/patents/US5092584?utm_source=gb-gplus-sharePatent US5092584 - Apparatus for testing and/or exercising the rotary neck muscles of the human body
