Description: Segment 1 The history of the patient is given by intertitle. General anaesthetic is administered, and the patient prepared for surgery. A skull is used to indicate various points of anatomical interest in the mastoid area. The operation begins, and an incision is made behind the patient's ear. The intertitles give detailed and technical descriptions of the steps of the procedure. The mastoid surface is exposed. The boundaries of the mastoid surface are described by intertitles. Time start: 00:00:00:00 Time end: 00:05:31:06 Length: 00:05:31:06 Segment 2 The operation continues. More incisions are made. The mastoid cortex is removed. The mastoid antrum is opened up. Time start: 00:05:31:06 Time end: 00:11:50:08 Length: 00:06:19:02 Segment 3 The final stages of the operation. Ossicles removed. Lumen of eustacian tube curretted. Wounds sutured. The bone cavity is packed with gauze. Time start: 00:11:50:08 Time end: 00:17:30:05 Length: 00:05:39:22