The metopic suture is located between the tubercles of the frontal bone. There are divergences regarding the exact time at which it closes, which ranges from the first to the tenth year of life, although it may persist into adulthood. This study was conducted on 134 dry crania from adult Brazilians, of which 95 were male and 39 were female. These were available in the anatomy laboratories of higher education institutions in Maceió, AL, Brazil. All the crania were examined macroscopically with regard to the presence (metopism: M) on absence of the metopic suture. M was considered to be complete (Mc) when it continued uninterruptedly from the nasium to the bregma and incomplete (Mi) when it was not present over its entire length. It was observed that Mc was present in 4.48% (6/134) of the skull examined, of which 50% (3/134) were male and 50% (3/134) were female. An incomplete metopic suture was found in 5.22% (7/144) of the crania and more frequently among males (3.73%; 5/134). Among the crania with a metopic suture, the dolichocephalic type predominated (7.46%) in relation to brachycephalic crania (1.49%) and mesocephalic crania (0.74%). There was no predominance of metopism between the sexes, while an incomplete metopic suture was slightly more common among males. 1. Introduction The frontal bone is a singular, median, and symmetrical bone that occupies the most anterior part of the cranium. It has joints with the parietal, ethmoid, sphenoid, nasal, zygomatic, lacrimal, and maxillary bones, thereby contributing towards uniting the neurocranium and the viscerocranium [1]. During the development stage, the frontal bone is a double bone, with right and left halves that grow together [2] and unite along the median line at the metopic suture [3]. This usually starts to undergo the fusion process at the age of two years [4] and may have completely fused by the age of six years [2, 5], eight years [4, 6], or ten years [1]. However, in approximately 8% of adults, the two halves of the frontal bone do not fuse [4], and the metopic suture persists. The suture may be incomplete or complete (when it extends from the nasium to the bregma), and this condition is known as metopism [7–9]. This name originates from the Greek word metopion, which means a space between the eyebrows [10]. Metopism has various degrees of incidence [11]: from 7%-8% among Europeans to 1% in Africans and 4-5% in Mongolians. Overall, the range of incidence can go from 1% to 12%, and it is slightly more prevalent among males [12]. The incidence of metopism and the difference in forms also vary
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