Fig. 2From: Cervical spine and muscle adaptation after spaceflight and relationship to herniation risk: protocol from ‘Cervical in Space’ trialSample marker set to determine the three-dimensional coordinate system for head and trunk segments and to calculate the helical axis of rotation. Depending on the position of the cameras in the room, the marker set needs to be adjusted and may differ slightly from the image (The images are original pictures taken by the team)Back to article page