The size and shape of the foramen magnum in man

Abstract

Background:The foramen magnum (FM) has garnered broad interest across the disciplines of anthropology, comparative anatomy, evolutionary biology, and clinical sciences. Most studies regarding the structure of the FM in humans have been intrapopulation morphometric studies rather than interpopulation morphologic studies. The few studies assessing the morphology of the foramen have utilized ambiguous and subjective descriptors to describe foraminal shape and are, consequently, difficult to reproduce. Therefore, detailed study of FM shape among craniofacially and geographically diverse populations through reproducible methods is warranted.Objectives:The aim of this study was to assess intersex and interpopulation differences in FM size and shape among diverse populations.Materials and Methods:The study analyzed 152 FMs of varied sex and race via traditional and geometric morphometric methods.Results and Conclusions:The study demonstrates that, within each distinct population, the size of the FM is significantly larger in males than in females; however, there are no significant differences in the shapes of the foramina between sexes. However, when comparing different populations to one another, there are significant differences with regard to both the size and shape of the FM. This study also presents a new model of FM ontogeny. Specifically, the growth occurring between the anterior and posterior foraminal boundaries before 5 years of age predicts the ultimate shape of the adult FM.

Foramen Magnum Variant With Elongation of the Anterior Notch

“…The shape of the East Asian FM was closest to the average FM shape, followed by Europeans and Bengalis. The African, Bengali, and Malayan populations tended to have a more elongated FM shape [2].…”

“…The bone around the FM results from descent of the occiput and growth of the petro-occipital and sphenopetrosal junctions. The FM size and area is determined by the endochondral parts of the basiocciput, exocciput, and supraocciput and the interoccipital synchondroses between them [1,2]. The FM is surrounded by the pars lateralis, pars squama, and pars basilaris components of the occipital bone.…”

Skeletal Characterization of the Fgfr3 Mouse Model of Achondroplasia Using Micro-CT and MRI Volumetric Imaging

“…The circumference length was measured along the surface geodesic path on the foramen boundary of the 3D rendered skull. The transverse and sagittal diameters (D t and D s ) of the foramen were also measured in 3D to calculate the area (¼ × π × D t × D s ) similar to a morphometric analysis described recently in a human study 48 .…”

Relations Between Foramen Magnum and Associated Structures Located Within the Skull Base of the Turkish Population

“…Kafa tabanı ile doğrudan ilişkili olan Chiari malformasyonu, hipoplazi, kleftler, aplasia, tonsiller herniasyon ve pek çok diğer patoloji ve malformasyonlar bulunmaktadır 1,12,14,[16][17][18][19] . Bu çalışmada literatürdeki çalışmalar referans alınarak LoC, C-FM, C-D, FMap, FMt ve FMa ölçümleri yapılmıştır 1,5,[9][10][11][16][17][18][19] . FM'un şekli ve boyutları cerrahi tekniği etkileyebilir ve bu konuda pek çok çalışma yapılmıştır 1,9,10,22 .…”

“…Bu çalışmada literatürdeki çalışmalar referans alınarak LoC, C-FM, C-D, FMap, FMt ve FMa ölçümleri yapılmıştır 1,5,[9][10][11][16][17][18][19] . FM'un şekli ve boyutları cerrahi tekniği etkileyebilir ve bu konuda pek çok çalışma yapılmıştır 1,9,10,22 . Basaran ve ark.…”