Bilateral caroticoclinoid foramen and unilateral abducens nerve canal found on the fetal skull – Case report

Ossifications of intracranial ligaments may have clinical meaning during various neurosurgical procedures and imaging diagnostics. Most of the observations of these ossifications reported in the literature are presented on material from adult humans. Descriptions made in the early stages of ontogenesis, when all kinds of intracranial bony bridges or intracranial ossifications are just taking shape, are rare. This case report analyses the formation of unilateral petrosphenoidal ligament ossification with coexisting sellar bridges on the fetal skull. Ossification (in progress) of the petrosphenoidal ligament with the canal formation for the abducens nerve was observed on the right side of this specimen. The bridge developing over the petrous apex bounded this atypical canal, or foramen, together with the postero-lateral surface of the dorsum sellae, petroclival suture (in the floor), and petrous apex. On this fetal skull, the dorsum sellae was not yet fully ossified. Moreover, bilateral formation of sellar bridges (between anterior and posterior clinoid processes) and caroticoclinoid foramina (between middle and anterior clinoid processes) was observed. Extensions of the anterior clinoid processes were not fully ossified, and the formation of the atypical bony bridges and foramina was captured (depicted) on this specimen just during ossification. Ossifications of the petrosphenoidal ligament may be observed in the fetal period and may be accompanied by sellar bridges. Knowledge of intracranial ligaments' mineralization may be vital in diagnostics and neurosurgical procedures in children and adults.