Which part of the brain is primarily drained by the straight sinus?

The straight sinus is a significant venous channel in the brain that primarily receives drainage from deep structures. Its primary function is to collect venous blood primarily from the great cerebral vein (also known as the vein of Galen) and the inferior sagittal sinus.

The structures that are drained by the straight sinus include parts of the cerebrum, particularly the medial aspects of the occipital and temporal lobes, as well as the deeper parts of the brain such as the thalamus and basal ganglia. However, the question specifically asks which part of the brain is primarily drained by this sinus, and the cerebrum is the broader region impacted due to the extensive drainage and involvement of various portions of its anatomy.

In contrast, the cerebellum, brainstem, and thalamus are drained primarily by other venous pathways. The cerebellum typically drains into the transverse and sigmoid sinuses, the brainstem's drainage is largely handled by the internal jugular vein system, and while the thalamus does contribute blood to the deep venous system, it is part of the cerebrum as a whole. Therefore, the primary association of the straight sinus with the cerebrum makes it the correct choice here.