Globographic Systems One axis is fixed to the globe's north-to-south-pole axis, rotation of
the distal segment around it results in the distal end of that segment travelling along "lines of
latitude" on the globe's surface.
One axis is fixed to the distal segment, aligned with its long axis; rotation of the distal segment
around it does not change the location of its distal end on the surface of the globe, but causes it
to spin around the segment's axis in that location.
One axis floats between the other axes or segments; rotation of the distal segment around it
causes its distal end to move along "lines of longitude" on the globe's surface.
Physiologic DoF of Motion A DoF of motion in which significant motion occurs without
injury. Segments are supposed to move this way and do so easily.
Non-Physiologic DoF of Motion A DoF of motion in which significant motion cannot occur
without injury to constraints of motion (articulation and links). Results in injury, but some
motion can occur if little enough.
Accessory DoF of Motion A DoF of motion in which significant independent motion does not
occur, but in which a small amount of motion accompanies physiologic motion in another DoF.
It is not the main motion, but allows for the motion to occur.
Types of Joints Ginglymi, condyloids, saddles, trochoids, enarthroses, and arthrodia (and
complex). Have different shapes of articulations and geometry of links. Constrain different DoFs
of motion. Classified based on which DoFs are physiologic vs non-physiologic.
Ginglymi (Ginglymus/Hinge) Joints Cylindrical articular surface. 1 rotational DoF orthogonal
to segment axes.
Physiologic DoF: SP rotation (flexion/extension).
Non-Physiologic DoF: CP rotation (varus/valgus), AP rotation (axial rotation), translation.
, Condyloids Joints Ovoid ball & socket. Bi-convex/bi-concave articulation. 2 rotational DOFs
orthogonal to segment axes.
Physiologic DoF: SP rotation (flexion/extension), CP rotation (abduction/adduction).
Non-Physiologic DoF: AP rotation (axial rotation), translation.
Saddles Joints 1 axis convex, another concave.
Physiologic DoF: SP rotation (flexion/extension), CP rotation (abduction/adduction).
Non-Physiologic DoF: AP rotation (axial rotation), translation.
Trochoids (Barrels) Joints Concentric cylindrical articular surfaces. 1 rotational DoF parallel
to segment axes.
Physiologic DoF: AP rotation (pronation/supination).
Non-Physiologic DoF: SP rotation, CP rotation, translation.
Enarthroses (Ball & Socket) Joints 3 rotational DoFs. Hemispherical articular surfaces.
Physiologic DoFs: CP rotation, SP rotation, AP rotation.
Non-Physiologic DoFs: translations.
Hip Joint Flexion-Extension: latitude.
IR-ER: long axis of femur and its axial rotation.
Abduction-Adduction: floating axis - longitude.
Gimbal lock at 90 degree abduction.
Gleno-Humeral (GH) Joint Horizontal abduction-adduction: latitude. Elbow moves
horizontally.
IR-ER: long axis of humerus and its axial rotation.
Elevation: floating axis - longiude.