Introduction: The tentorium is a membrane which covers the cerebellum. It separates the cerebrum from the cerebellum. The term tentorium was first coined by Winslow. The tentorium is attached to the temporal, occipital, and sphenoid bones. All of the tentorial margins, except the free edges bordering the incisura, are rigidly attached to the cranium. The anterior border is attached to the petrous ridge. The lateral and posterior borders are attached to the inner surface of the occipital and temporal bones along the internal occipital protuberance and to the edges of the groove for the transverse sinus. Aim of the Study: To determine the incidence of venous sinuses within the tentorium cerebelli. Identify the location, configuration and size of the sinuses within the tentorium. Materials and Methods: In this study, 100 human cadaveric brains of both male and female that underwent autopsy within 12-48 hrs after death were studied in the year 2016-2018 in Department of Neurosurgery, Government Mohan Kumaramangalam Medical College. Salem. Skullcap was opened in a circular manner. The frontal lobes were lifted after opening the dura mater and the anterior falx was cut. The brain stem was cut axially just above the level of tentorial incisura. Results: Variations of tentorial venous sinus in cadaver cerebellar tentoria were examined in 100 autopsies. Venous sinuses were present in tentorium in 91 (91%) cadavers and absent in 9 cadavers. There were 145 tentorial venous sinuses in 91 cadavers. Of these sinuses, 81 (55.9%) occurred on the left side, 64 (44.1%) occurred on the right side. Conclusion: Incidence of venous sinuses in tentorium cerebelli is 91%. Middle one-third of tentorium cerebelli is the least vascular portion. These findings will be useful for procedures that require sectioning of the tentorium. These sinuses serve as important collateral channels when the straight sinus or torcular herophili is occluded by pathological processes. 

Keywords: Tentorium Cerebelli; Venous Sinus; Skull Injury; Congenital Malformations of the Brain.