Foramen ovale (FO) serves as an important landmark for neurosurgeons in the surgical procedures of the trigeminal nerve. FO is the transition point between intracranial and extracranial structures. The information about anatomical variations of foramen ovale have surgical importance in different methods such as percutaneous trigeminal rhizotomy, biopsy of cavernous sinus tumour and anaesthesia of the mandibular nerve. FO variation is quite rare. It is unknown by many researchers and clinicians. It is thought that divided FO variations emerge as a result of the ossification of pterygospinous ligament. Clinicians must know that such variation may occur in surgical operations on skull base.
Foraman ovale, variation, sphenoid bone, base of skull, ossification