Tympanic membrane retraction tensa. Tympanic membrane retraction is fairly common and has been observed in one quarter of a population of British school children. Retraction of both eardrums is less common than having a retraction in just one ear. It is more common in children with cleft palate. Tympanic membrane retraction also occurs in adults. Attempts have been made to categorise the extent of tympanic membrane retraction though the validity of these classifications is limited. The majority of tympanic membrane retractions do not cause any symptoms. Some cause hearing loss by restricting sound-induced vibrations of the eardrum. Permanent conductive hearing loss can be
Common name not always English. For example, "Dikkop" is the centuries-old South African vernacular name for their two local species: "Burhinus capensis" is the Cape dikkop (or "gewone dikkop", not to mention the presumably much older Zulu name "umBangaqhwa"); "Burhinus vermiculatus" is the "water dikkop". The thick joints in question are not even, in fact, the birds’ knees, but the intertarsal joints—in lay terms the ankles. Furthermore, not all species in the genus have “thick knees”, so the thickness of the "knees" of some species is not of clearly descriptive significance. The family Burhinidae has members that have various common names even