AnatomyPlot3D[{Entity["AnatomicalStructure", "Humerus"],
Entity["AnatomicalStructure", "Radius"],
Entity["AnatomicalStructure", "Ulna"],
Entity["AnatomicalStructure", "Scapula"]}]
How can I move the humerus in the shoulder joint, while the radius and ulna stay attached? Subsequently, how to move the radius-ulna pair independently of the humerus? I'm aware that rotations will have to be used (e.g. 3 DOF for humerus), but I'm unaware how to set the attachment point from where the rotations will happen (shoulder joint and radioulnar joint for humerus and radius-ulnar pair respectively).

Rotate[g,θ,w,p]. Apply it to the elementsginCases[ap, {__, _[_GraphicsComplex, __]}, Infinity], whereapis the plot above. You will need to useTranslate[]as well. – Michael E2 Nov 19 '18 at 12:22