Dundyuk-Berezina S. Anatomical features of small bones of the facial skull in the perinatal period of ontogenesis. – Qualification scientific work as a manuscript.

In order to establish chronological sequence of temporal transformations of the anatomical features in the small bones of the facial part of the skull in fetuses and newborns, the research was performed on 57 objects of human fetuses aged from 4 to 10 months and 7 newborns (5 isolated organocomplexes in particular). The research was carried out by means of up-to-date and adequate morphological methods of examination: macro- and microdissection, X-ray examination, computed tomography, morphometry, statistical processing. The lateral, temporal and orbital surfaces and the two processes – frontal and temporal – are found to be clearly distinguished in the perinatal period of ontogenesis. Frontal-zygomatic suture in the form of an oblique line is registered in 56.2 % cases, the suture in the form of a «pyramid» – in 43.8 %. Temporal-zygomatic sututre in the form of an oblique line is found in 44 % cases, the sututre in the form of a wavy line – in 56 %. Typical forms of the zygomatic-maxillary suture are the suture in the form of wavy (41.8 %) and zigzag (37.6 %) lines, a variant form is the suture in the form of an oblique line (20.6 %). In the perinatal period of ontogenesis, two surfaces of the nasal bone are already clearly visible: anterior and posterior. The nasal bones form the internasal suture of two shapes: in the form of longitudinal straight line (58.4 % cases) and in the form of a line with longitudinal-lateral convexity (41.6 %). The average amount of the nasal-maxillary suture in the form of a longitudinal straight line are 57.8 % cases, the suture in the form of a longitudinal wavy line – 42.7 %. During the fetal and early neonatal periods of ontogenesis morphometric parameters (height and width) of the zygomatic and nasal bones increase gradually. Meanwhile, these parameters have periods of an intensive increase. It is the period from the 5th to the 6th month of development, specific for the height of the zygomatic bone; from the 6th to the 7th month of development – for the width of the zygomatic bone; from the 6th to the 7th month of development, and from the 10th month to the neonatal period – for the height of the nasal bone, from the 7th to the 8th month of development – for the width of the nasal bone. The period of a relative enlargement specific for the width of the nasal bone was from the 6th to the 7th month. Its size does not practically change in this period of development. Small bones of the facial skull in the perinatal period are characterized by asynchronous increase of density of their osseous tissue. During the perinatal period the bone density of the zygomatic bones increases by 34.2 % (the right one) and 42.4 % (the left one), the right and left nasal bones – up to 90 %, vomer – up to 100 %, and the right and left lacrimal bones increase is 118.5 % and 121 % respectively. The zygomatic and nasal bones are radiopaque since the 4-month fetuses, the vomer – since the 5th month, the lacrimal bones – since the 6th month.