Os parietale divisum

Abstract

Divisions of the parietal bone are extraordinarily rare, and have been described previously only in skull specimens in the anatomical literature. We report a case of os parietale divisum (divided parietal bone) in an infant with plagiocephaly. A 36-weeks gestation male with multiple congenital anomalies presented to the deformational plagiocephaly clinic at 11 weeks of age. CT imaging demonstrated a suture dividing the left parietal bone into two segments. He had a plagiocephalic appearance, with the greater occipital and parietal protuberances ipsilateral to the abnormal left parietal suture, and a correspondingly flatter right occiput. Head circumference was in the normal range, and the anterior fontanelle was patent and of normal size. He had mild right-sided right frontal and malar protuberance. Mandibular asymmetry was noted with a chin-point to the right of midline. He had a left-sided head tilt. He was treated with cranial molding helmet therapy for his head shape and physical therapy for his head tilt. After 16 months of helmet therapy, he had little improvement of his head shape. This case is an in vivo presentation of a rare variant, os parietale divisum.

Morphological and Molecular Evidence Reveals Recent Hybridization Between Gorilla Taxa

“…Moreover, the presence of an extremely rare sutural variant, os parietale divisum , in two eastern lowland gorillas—one of which expresses the trait bilaterally—also supports this scenario. Os parietale divisum is present in humans and other primates at an incidence well below 1%; few cases (overwhelmingly unilateral) have been described in the anatomical literature (Turner 1890; Shapiro 1972; Hrdlicka 1903; Berry 1910; Fenton et al 2000; Bessell‐Browne and Thonell 2004; Becker et al 2005). Complete divisions in apes have been reported once in the literature, in two orangutans and a chimpanzee—these were both unilateral (Hrdlicka 1903).…”

“…Complete divisions in apes have been reported once in the literature, in two orangutans and a chimpanzee—these were both unilateral (Hrdlicka 1903). Although this condition is considered to have no functional consequences (Hauser and De Stefano 1989), it has recently been shown that it can be associated with other congenital anomalies (Becker et al 2005). As such, it may result from, or at least be correlated with, wider developmental abnormalities in these two specimens.…”

Phenotypic traits of primate hybrids: Recognizing admixture in the fossil record

“…This finding is consistent with what was observed in both baboons and in wildebeest, but in addition there were two individuals with an extremely rare sutural anomaly, completely divided parietal bones (Os parietal divisum). This anomaly occurs at a frequency of <0.001 in humans, 68 with only a few cases described in the anatomical literature for modern humans and apes. This condition does not appear to have any functional consequences, although it can be associated with other congenital anomalies.…”

“…This condition does not appear to have any functional consequences, although it can be associated with other congenital anomalies. 68 These nonmetric anomalies were not evenly distributed on the landscape. Both sutural anomalies and hybridlike patterning of supernumerary teeth were shown to occur at very high frequencies in eastern lowland gorillas (G. b. graueri), the former at 45% on average across all eastern lowland localities and the latter as high as 13% in a single locality, MwengaFizi (Itombwe).…”

Anomalous Parietal Suture Mimicking Skull Fracture

“…Several articles have described the finding of anomalous sutures in children with plagiocephaly by radiographic evaluation. 7,8,9 Skull fractures in nonaccidental trauma tend to be linear and are more frequently multiple, bilateral, or cross suture lines than in accidental trauma. In addition, the parietal and occipital bones were the most frequently involved, although this is also the case with accidental fractures as well.…”