340 THE EAR Fig, 174. Radical mastoid operation. A, Skin incision. B, Area of operation exposed. C, Mastoid antrum opened. 0, Outer or lateral part of posterior bony meatal wall removed, but inner end, or bndge, remains. Drumhead is visible. E, Most of the bridge has now been removed, body of the incus and head of the malleus are revealed. F, Radical operation completed. Malleus and incus, with the drumhead, have been removed, and facial spur lowered. Prominence of lateral canal, facial nerve, stapes, promontory and the niche leading to the round window can all be seen on medial wall of operation cavity.