A constancy of mineral contents in human auditory ossicles.

To determine element contents of auditory ossicles, the malleus and incus were removed from 27 subjects which died at the ages between 40 and 98 years old, and their elemental contents were analyzed by inductively coupled plasma atomic emission spectrometry. It was found that the relative contents (RCs) of calcium and phosphorus were very high in the malleus and incus. The RCs of calcium and phosphorus in the ossicles corresponded to one-and-a-half-fold amounts as compared with the spongy bone of human cervical vertebrae. The mass ratio of calcium per phosphorus in the ossicles was almost the same as that of crystalline calcium phosphate hydroxyapatite. Relationships between the aging and RCs of minerals and between both the sexes in the ossicle were examined. It was found that both the RCs of calcium and phosphorus in the malleus and incus were really constant at the age over 40 years old, and that there was no significant difference of the mineral contents between men and women.