A short<unk> m on the floor of the left maxillary sinus, depicted in a regular dental x-ray film (top), a photograph taken during a sinus augmentation procedure (middle) and in a cone beam CT scan taken for preoperative evaluation (bottom). In anatomy,<unk>  (or maxillary sinus<unk> , singular<unk> m) are fin-shaped projections of bone that may exist in the maxillary sinus, first described in 1910 by Arthur S.<unk> , an anatomist at King's College in London. The presence of<unk>  at or near the floor of the sinus are of interest to the dental clinician when proposing or performing sinus floor elevation procedures because of an increased likelihood of surgical complications, such as tearing of the Schneiderian membrane. The prevalence of<unk>  in relation to the floor of the maxillary sinus has been reported at nearly 32%.
Underwood's septa
Schneiderian membrane
Curschmann's spirals
Dennie–Morgan fold
Mees' lines
Bird fancier's lung
Surfer's knots
Ossification center