The falx cerebri is a two-layered, sickle-shaped dural septum, which descends from the skull vault into the longitudinal cerebral fissure. One of the two layers is seen covering the medial surface of the left cerebral hemisphere. Anteroinferiorly, the falx is narrow and attached firmly to the crista galli of the ethmoid bone. The posterior part of the falx cerebri is broader and is attached in the median plane to the superior surface of the tentorium cerebelli, a sloping fold of the dura that overlies the cerebellum like a tent. Along its upper margin the two layers of the falx separate, to enclose the superior sagittal sinus. In the specimen this sinus is opened, exposing openings of superior cerebral veins and clusters of arachnoid granulations. The free, concave lower margin of the falx cerebri encloses the inferior sagittal sinus. The straight sinus, located at the site of attachment of the falx cerebri to the tentorium cerebelli, has been opened. The straight sinus, formed by the union of the inferior sagittal sinus and the great cerebral vein, is enclosed jointly by the falx cerebri and tentorium cerebelli at their site of attachment. The great cerebral vein can be seen curving below the splenium of the corpus callosum to empty into the straight sinus.

The cerebellomedullary cistern (cisterna magna) is the largest of the spaces containing cerebrospinal fluid between the arachnoid mater and the pia mater, and is located between the cerebellum and the medulla oblongata. It continues downwards without interruption into the subarachnoid space surrounding the spinal cord, and upwards and laterally into the subarachnoid space of the posterior cranial fossa. The cistern is traversed by delicate connective tissue trabeculae, which bridge across the interval between the arachnoid mater and the pia mater.