(also known as inferior longitudinal sinus), within the human head, is an area beneath the brain which allows blood to drain outwards posteriorly from the center of the head. It drains (from the center of the brain) to the straight sinus (at the back of the head), which connects to the transverse sinuses.

The inferior sagittal sinus courses along the inferior border of the falx cerebri, superior to the corpus callosum.

It receives blood from the deep and medial aspects of the cerebral hemispheres and drains into the straight sinus.

Yasargil classified falcine meningiomas into outer and inner types. The former arise from the main body of the falx in the frontal (anterior or posterior), central parietal, or occipital regions, whereas inner falcine meningiomas arise in conjunction with the inferior sagittal sinus. ¹⁾.