Joint/element (hierarchy) | Anatomical meaning of rotation about axis | Zero-point for rotations |
---|---|---|
Global coordinate system (top) | ||
x-axis | - | - |
y-axis | - | - |
z-axis | - | - |
1st thoracic vertebra (1st order) | ||
x-axis | Long axis rotation of vertebral column (roll) | Aligned to global x |
y-axis | Lateral undulation of vertebral column (yaw, +: undulation to the right) | Aligned to global y |
z-axis | Pitch of vertebral column (+: decrease of head-support distance) | Aligned to global z |
Scapular center of rotation/scapula (2nd order) | ||
x-axis | Inward (+) /outward (-) rotation about long axis of scapula | Scapula is not rotated (long axis of scapula parallel to thoracic y-axis) |
y-axis | Abduction (-) /adduction (+) of scapula (yaw) | Scapula is not abducted |
z-axis | Protraction (-) /retraction (+) of scapula (pitch) | Scapula is vertical (in perfect dorso-ventral orientation) |
Glenohumeral joint/humerus (3rd order) | ||
x-axis | Long axis rotation of humerus (roll, +: outward rotation) | Humerus is not rotated (epicondyles aligned in frontal plane) |
y-axis | Humeral abduction (-) /adduction (+) from scapular plane (yaw) | Humerus is in scapular plane |
z-axis | Humeral protraction (-) /retraction (+) (flexion in glenohumeral joint, pitch) | Humerus is orientated vertical (long axis parallel to scapula long axis) |
Sterno-clavicular joint/clavicle (2nd order) | ||
x-axis | Rotation about long axis of clavicle (+: caudal rotation) | The curvature of the clavicle is pointing ventral |
y-axis | Anterior (+) /posterior (-) displacement of acromio-clavicular joint relative to manubrium sterni | Clavicle is pointing lateral and forms 90° angle to long axis and y-axis of the 1st thoracic vertebra |
z-axis | Dorso (-) /ventral (+) displacements of acromio-clavicular joint relative to manubrium sterni | Clavicle is pointing lateral and forms 90° angle to long axis and y-axis of the 1st thoracic vertebra |