Falx cerebelli

The falx cerebelli is a small infolding of the dura in the sagittal plane over the floor of the posterior cranial fossa. It partially separates the two cerebellar hemispheres .

Gross anatomy

The falx cerebelli is attached posteriorly in the midline to the internal occipital crest of the occipital bone where it contains the occipital sinus . Its anterior edge exists freely between the partially separated cerebellar hemispheres in the posterior cerebellar notch. Superiorly it is attached to the tentorium cerebelli . Inferiorly, it extends to the posterior edge of the foramen magnum. At this point it sometimes divides into two separate parts which extend anteriorly either side of the foramen magnum . Abnormalities of the falx cerebelli may be seen in normal individuals but are more common in the setting of brain or craniofacial abnormalities (particularly posterior fossa abnormalities) .

  • anteriorly: cerebellum
  • posteriorly: occipital bone
  • inferiorly: foramen magnum 
  • superiorly: tentorium cerebelli 

Variant anatomy

  • morphology can vary from linear to shapes resembling the letters “Y,” “V,” or “U”
  • duplication or triplication of the falx cerebelli
  • absence of the falx cerebelli may be seen in many instances but is present in nearly 100% of patients with Chiari II malformation

Related pathology