Pequliarities of Morphogenesys and Topography of Infrahyoid Triangles in Human Prefetuses and Fetuses

Abstract

The aim: To investigate morphology and developmental features of anatomical structures in the infrahyoid triangles of human neck during prefetal and fetal periods of human ontogenesis. Materials and methods: We have studied 30 specimens of human prefetuses from 7th till 12th week (16,0-82,0 mm of parieto-coccygeal length (PCL)) and 30 human fetuses aged from 4th till 10th month (84,0-360,0 mm PCL) of intrauterine development by the means of macro-, microscopy, morphometry, three-dimensional remodeling and statistical analyses. Results: We can observe anterior triangle in human fetuses after the time when common precursor muscular mass splits into two: the anterior and posterior portions which will give rise to the sternocleidomastoid and trapezoid muscles accordingly. The area index of the central triangle in human fetuses 4th – 10th month of intrauterine development shows the increasing tendency with the highest rates at 8th–10th months period – 1100-1200 mm2. The angulated course of omohyoid muscle is visible at late prefetal and early fetal periods (3-4th month; 80,0-130,0 PCL) as well as the presence of intermediate tendon. Peaks of the area of sternocleidomastoid region area evaluation was observed in 190,0-210,0 mm PCL and 260,0-270,0 mm PCL human fetuses; 6th and 7,5th months accordingly. Conclusions: The critical periods for the AT and SCM regions should be considered 6th and 8th months of the IUD. Prefetal period shows the presence of AT and border structure for the IH neck – precursor of HB. Fetal period of IUD (4th – 10th months of IUD) should be considered as such that represents an adult-alike morphology of IH neck: presence of IH triangles with fully developed vascular, muscular and fascial content.

Peculiarities of the Sources of Origin and Morphogenesis of the Human Mandible

“…The foci of direct osteogenesis in the upper jaw appear a week later after the fusion of the maxillary processes with the nasal and medial frontal processes. The researchers of this issue state [5] that the foci of the membranous ossification in both jaws are clearly determined in the embryos of the 8 th week of development stained with alizarin and cleared in xylene, the parietal-coccygeal length of these embryos is 23,5 mm. At the same time, there are several ossification centers in the upper jaw which develop from the heterogeneous anlages.…”