An anchoring system for cannulas or tools to be inserted into a surgical workspace in the body, particularly the brain, of a patient. The system comprises a grommet which may be fixed to the skull to both secure the system to the skull and protect the skull opening from passage of cannulas and tools, a resilient clip with grasping jaws adapted to firmly grasp a cannula or tool, and a flexible membrane secured to the outer rim of the grommet and the clip.
