Development of structural elements of the middle ear in humans
Kosiagina, E.B.
Arkhiv Anatomii Gistologii i Embriologii 77(9): 73-79
1979
ISSN/ISBN: 0004-1947 PMID: 496670 Document Number: 142957
The form, dimentions and relations of structural elements of the tympanic cavity, its space orientation and development of pneumatic cells were studied in embryos 7-37 mm long, in 838 temporal bones, in 840 acoustic bones and in 288 embryonic and human skulls of different ages. Dimentions of the tympanic cavity and those of the structures situated within it stabilize during the intrauterine period. At the same time, certain relations are established among the acoustic bones and other structures within the tympanic cavity, and among the contents of the tympanic cavity and its walls. Individual changes of the tympanic structural elements and their relations occur during the 1st half of intrauterine life. Asymmetry of the tympanic components is evident during the 1st months of fetal life, its absolute value and rate of occurence do not change considerably during ontogenesis. Even though at birth the tympanic cavity and its structural elements have dimensions corresponding to those of an adult, the formation of the middle ear is not complete during the intrauterine period. After birth the walls of the tympanic cavity are forming, its position in the skull is changing, the pneumatic cells of the mastoid and other parts of the temporal bone are developing. Pneumatization can start from the 1st months of the infant's life. The degree and dimentions of the pneumatic cells increase with age.