title: Normal variants and congenital anomalies in the region of the obelion.
abstract: A number of anatomic bony variants and several congenital anomalies are known to occur at the level of the obelion, that is, in the posterior interparietal region of the head, a short distance in front of the lambda. Among them are: (1) remnants of the embryonic parietal incisura, including parietal fissure, small and large parietal fontanelle, obeliac bones, persistant midline parietal foramen, and small and large parietal foramina; (2) encephalomeningoceles and related defects, including true encephaloceles, herniation of midline intracranial cysts (diencephalic and Dandy Walker cyst), epicranial arachnoid cysts, and scalp defects with ectopic glial tissue; and (3) congenital scalp and skull defects (cutis aplasia congenita). A review of these defects is presented with some illustrative examples not previously reported.
mesh_terms: D000293:Adolescent; D001927:Brain Diseases / Q000000981:diagnostic imaging; D002493:Central Nervous System Diseases / Q000000981:diagnostic imaging; D002648:Child; D002675:Child, Preschool; D003560:Cysts / Q000000981:diagnostic imaging; D004677:Encephalocele / Q000000981:diagnostic imaging; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D011859:Radiography; D012535:Scalp / Q000002:abnormalities; D012886:Skull / Q000002:abnormalities / Q000000981:diagnostic imaging*