The falx cerebelli is a small sickle-shaped fold of

dura mater In neuroanatomy, dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. ...

projecting forwards into the posterior cerebellar notch as well as projecting into the vallecula of the cerebellum between the two cerebellar hemispheres. The name comes from two Latin words: ''falx'', meaning "curved blade or scythe", and ''cerebellum'', meaning "little brain".

Anatomy

The falx cerebelli is a small midline fold of dura mater projecting anterior-ward from the skull and into the space between the cerebellar hemispheres. It generally measures between 2.8 and 4.5 cm in length, and approximately 1–2 mm in thickness.

Attachments

Superiorly, it (with its upwardly directed base) attaches at the midline to the posterior portion of the inferior surface of the tentorium cerebelli. Posteriorly, it attaches to the

internal occipital crest In the occipital bone, the lower division of the cruciate eminence is prominent, and is named the internal occipital crest; it bifurcates near the foramen magnum and gives attachment to the falx cerebelli; in the attached margin of this falx is th ...

; the inferior-most extremity of its posterior attachment frequently divides into two small folds that terminate at either side of the foramen magnum.

Anatomical relations

The

occipital sinus The occipital sinus is the smallest of the dural venous sinuses. It is usually unpaired, and is sometimes altogether absent. It is situated in the attached margin of the falx cerebelli. It commences near the foramen magnum, and ends by draining in ...

is contained within the posterior extremity of the falx cerebelli where it attaches to the internal occipital crest.

Anatomical variation

In its lower portion the falx cerebelli diminishes very rapidly in height and as it descends, it can divide into two smaller ''folds'' or ''diverging limbs'', which are lost on the sides of the foramen magnum. Other variations such as duplication, triplication, absence, and fenestration are much less common. As dural venous sinuses are concurrent with the development of dural folds, duplication of the falx cerebelli is usually associated with duplicated occipital sinus.Shoja MM, Tubbs RS, Shokouhi GH, Ashrafian A, Oakes WJ. Abstract presented at the 23rd Annual Meeting of the American Association of Clinical Anatomists. Milwaukee, Wisconsin: 2006. A triple dural-venous variation in the posterior cranial fossa: A duplicated plus accessory falx cerebelli and an aberrant venous sinus. Knowledge of these variations is important in preventing iatrogenic injuries in this region.

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