The common mount surgery tool has a holder (9) to position the working end to the operation site and with a selection of tool heads which can be extended into selected working positions. The tool mount can be rotated about its middle axis to position each tool as required. The ultrasonic tool is electrically insulated from the HF tool. The HF tool has a ball shaped end or can be fitted with a hooked end to collect tissue samples. The tool mount includes suction ducts and rinsing ducts.