Abstract: This instrumentation comprises valves (2) for shifting aside tissues and vessels, pins for fixing each valve (2) to the spine, each valve (2) comprising for this purpose sleeves (6) in which the pin (5) is slidable; the instrumentation further comprises, for each valve (2), an articulated device (7) comprising a clamp (12) for clamping a rod (13) fixed to the valve (2); the clamp (12) may be articulated to a ball and oriented in all directions in space while the rod (13) and the valve (2) are adjustable in translation in the clamp (12); the articulated devices (7) are adjustably slidably mounted on a support frame (8). The instrumentation further comprises a push member which is capable of bearing against the valves (2) and preventing them from slipping on the surface of the spine while they are being placed in position. This device permits conveniently orienting the valves (2) in all directions and in translation.