Final answer:
Cranial sinuses are positioned between two normally fused layers of the dura mater in the cranial cavity.
Step-by-step explanation:
Cranial sinuses, specifically dural venous sinuses, are located between two layers of the dura mater, which is the tough outer covering of the brain within the skull. The meningeal layers of the superior sagittal sinus, for instance, show that the dura mater is adjacent to the inner surface of the cranium with the pia mater adjacent to the surface of the brain. Between them lies the arachnoid and the subarachnoid space. An arachnoid villus, shown in the diagram, protrudes into the dural sinus to allow cerebrospinal fluid (CSF) to filter back into the blood for drainage.
The cranial sinuses are located between the layers of meninges in the cranial cavity. Specifically, they are located between the dura mater, the outermost layer of the meninges that is adjacent to the inner surface of the cranium, and the arachnoid and subarachnoid space, which are between the dura mater and the pia mater, the innermost layer of the meninges that is adjacent to the surface of the brain.