A reverse shoulder assembly comprising: a glenoid component (100, 200, 900) comprising a glenosphere (110, 210, 910) and a glenoid plate (120, 220, 920); and a humeral component (300, 700, 800) comprising a humeral liner (310, 710, 810) and a humeral stem (305, 705, 805), wherein the glenosphere (110, 210, 910) comprises an articulating surface (115, 215, 915) having a convex geometry, wherein the humeral liner (310, 710, 810) comprises an articulating surface (315, 715, 815) having a concave geometry, and wherein the articulating surface (115, 215, 915) of the glenosphere (110, 210, 910) is adapted to articulate with the articulating surface (315, 715, 815) of the humeral liner (310, 710, 810), characterised in that the articulating surface (115, 215, 915) of the glenosphere (110, 210, 910) comprises a motion inducing element (140, 240, 940) and that the articulating surface (315, 715, 815) of the humeral liner (310, 710, 810) comprises a motion inducing humeral liner surface (340, 750,850), wherein the motion inducing element (140, 240, 940) and the motion inducing humeral liner surface (340, 750,850) are sufficiently designed so that, when the glenoid component (100, 200, 900) is implanted in a glenoid, and when the humeral component (300, 700, 800) is implanted in a humerus, an interaction between the motion inducing element (140, 240, 940) and the motion inducing humeral liner surface (340, 750, 850) alters the abduction motion of the humerus relative to a scapula, into either (a) a forward flexion motion of the humerus relative to the scapula, (b) an external rotation motion of the humerus relative to the scapula, or (c) an external rotation motion of the humerus relative to the scapula and a forward flexion motion of the humerus relative to the scapula, wherein the motion inducing element (140, 240, 940) is sufficiently sized and positioned on the articulating surface (115, 215, 915) of the glenosphere (110, 210, 910) to alter the direction of the induced motion at varying humeral positions, and wherein between about 30 degrees and about 90 degrees abduction motion of the humerus relative to the scapula, the motion inducing element (140, 240, 940) is adapted to initially engage the motion inducing humeral liner surface (340, 750, 850). a glenoid component (100, 200, 900) comprising a glenosphere (110, 210, 910) and a glenoid plate (120, 220, 920); and a humeral component (300, 700, 800) comprising a humeral liner (310, 710, 810) and a humeral stem (305, 705, 805), wherein the glenosphere (110, 210, 910) comprises an articulating surface (115, 215, 915) having a convex geometry, wherein the humeral liner (310, 710, 810) comprises an articulating surface (315, 715, 815) having a concave geometry, and wherein the articulating surface (115, 215, 915) of the glenosphere (110, 210, 910) is adapted to articulate with the articulating surface (315, 715, 815) of the humeral liner (310, 710, 810), characterised in that the articulating surface (115, 215, 915) of the glenosphere (110, 210, 910) comprises a motion inducing element (140, 240, 940) and that the articulating surface (315, 715, 815) of the humeral liner (310, 710, 810) comprises a motion inducing humeral liner surface (340, 750,850), wherein the glenosphere (110, 210, 910) comprises an articulating surface (115, 215, 915) having a convex geometry, wherein the humeral liner (310, 710, 810) comprises an articulating surface (315, 715, 815) having a concave geometry, and wherein the articulating surface (115, 215, 915) of the glenosphere (110, 210, 910) is adapted to articulate with the articulating surface (315, 715, 815) of the humeral liner (310, 710, 810), characterised in that the articulating surface (115, 215, 915) of the glenosphere (110, 210, 910) comprises a motion inducing element (140, 240, 940) and that the articulating surface (315, 715, 815) of the humeral liner (310, 710, 810) comprises a motion inducing humeral liner surface (340, 750,850), wherein the humeral liner (310, 710, 810) comprises an articulating surface (315, 715, 815) having a concave geometry, and wherein the articulating surface (115, 215, 915) of the glenosphere (110, 210, 910) is adapted to articulate with the articulating surface (315, 715, 815) of the humeral liner (310, 710, 810), characterised in that the articulating surface (115, 215, 915) of the glenosphere (110, 210, 910) comprises a motion inducing element (140, 240, 940) and that the articulating surface (315, 715, 815) of the humeral liner (310, 710, 810) comprises a motion inducing humeral liner surface (340, 750,850),