Objective: To study the development of the incudostapedial joint in human embryos and foetuses.
Material and method: 46 temporal bones with specimens between 9 mm and newborns were studied. The preparations were sliced serially and dyed using the Martins trichrome technique.
Results: The incudostapedial joint takes on the characteristics of a spheroidal joint at 16 weeks of development. The cartilage covering the articular surfaces is formed by different strata that develop in succession: the superficial stratum at 19 weeks, the transitional between 20 and 23 weeks, and the radial from 24 weeks on. The subchondral bone develops after 29 weeks by the mechanisms of apposition and extension of the periosteal and endosteal bones, but it is not until week 34 that it completely covers the articular surfaces, following constitution of the bone fascicles transmitting the lines of force. The articular capsule is formed from the inter-zone, the surface zone develops the capsular ligament, and the internal surface develops the synovial membrane.
Conclusions: At the time of birth, the incudostapedial joint is completely developed.