A rare variation of the posterior cranial fossa: duplicated falx cerebelli, occipital venous sinus, and internal occipital crest.

Folds of the meningeal layer of the dura mater, the falx cerebri and tentorium cerebelli, traverse the vertebrate intracranial cavity and thus compartmentalise the brain. The falx cerebelli, another dural fold, is found in the posterior cranial fossa and attaches to the inferior aspect of the tentorium cerebelli and to the internal occipital crest. We present a case of a duplicated falx cerebelli, occipital venous sinus and internal occipital crest that was detected upon routine dissection of a male cadaver. Since haemorrhage of a dural venous sinus can be a fatal complication of posterior cranial fossa surgery, knowledge of venous sinus variations in this region may prevent unpredictable complications during intracranial procedures.