Final answer:
The cranial dural septa are infoldings of the dura mater that create partitions within the brain, supporting brain structure and encapsulating the venous dural sinuses which help in draining blood from the brain.
Step-by-step explanation:
Cranial dural septa are infoldings of the dura mater, one of the meningeal layers that encapsulate the brain. These septa form partitions that fit into the large crevasses of the brain, helping to support the brain's structure and containing the dural sinuses. Notably, there are two main infoldings going through the midline separations of the brain: one that forms a shelf-like structure between the occipital lobes of the cerebrum and the cerebellum, and another that surrounds the pituitary gland. The cranial dural septa thus play a key role in supporting the venous sinuses which are involved in the drainage of blood from the central nervous system.
These septa also work in conjunction with the other layers of the meninges, namely the pia mater and the arachnoid mater, which are adjacent to the surface of the brain and containing the subarachnoid space respectively. The arachnoid villi emerging into the dural sinus facilitate the filtration of cerebrospinal fluid (CSF) back into the blood for drainage.