engleski

New insights into the development of the sphenoid bone

Introduction: The development of human skull has been the subject of many studies so far, since this forms the basis for understanding the structure of adult skull and the development of new surgical approaches to intracranial structures. However, there is little literature related to the development of the sphenoid bone during fetal and neonatal periods. The sphenoid bone and its large wings in particular are a place of great clinical interest because of the vicinity of the middle cerebral artery and the trigeminal nerve. There are also studies reporting meningiomas and fractures of the sphenoid bone. In this study, we traced the development of large wings and Turkish saddle of the sphenoid bone by microCT scanning. Material and methods: In the study we included a total of 17 isolated sphenoid bones of fetuses and newborns from 160 to 520mm length from the bone collection of the Department of Anatomy at the University of Zagreb Medical School. Ethical approval was obtained from the Research Ethics Committee of the University of Zagreb. The bones consisted of separate large wings and a central portion with Turkish saddle and small wings. The bones were scanned by microCT, and we recorded the length, width and weight of the large sphenoid wing as well as the distance between the foramen rotundum and foramen ovale. In the central part, we measured the width of dorsum sellae, the width of medial clinoid sequels and the antero-posterior diameter of the Turkish saddle. Results: The development of large sphenoid wings is not linear, but rather represented by a curve. The period of the largest increase in length and width of large wings occurs when the fetus measures from 300 to 430mm, when the change of intensity is more pronounced in length growth. At the same time the greatest changes in weight of large sphenoid wings occur in the period when the fetus measures from 400 to 500mm. The growth rate of the distance between foramen rotundum and foramen ovale shows smaller variations in the intensity of changes. Changes of basic dimensions of Turkish saddle were most intensive in the period from 400 to 500mm fetus size, which is best visible in the antero-posterior diameter. Comparing the absolute increase of the parameters described in the aforementioned period, we found that the largest increase occured in the weight of large sphenoid wings and that it is nearly tenfold greater than the increase in length or width of large sphenoid wings. Conclusion: Analyzing the results, we concluded that the development of sphenoid bone is not characterized by a constantly equal increase, and that the period of greatest intensity of development differs with regard to specific parameters. We found that the most rapid development of large sphenoid wings in length and width precedes the fastest increase of their weight. We also found that the highest intensity of growth in large sphenoid wings occurs earlier than in the central part of sphenoid bone. We conclude that the development of sphenoid bone is a complex process that is not parallel and equal to the development of the entire skull and also not uniform in all of its constituent parts. This study of the sphenoid bone development allows us to predict the size and position of certain structures of neurocranium, thus contributing to better understanding of the structure of the skull and, consequently, better planning and development of new surgical approaches.

sphenoid wing; sphenoid bone; skull development

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