Final answer:
The hollow spaces within the brain are known as ventricles, which consist of four main chambers responsible for producing and circulating cerebrospinal fluid through the central nervous system.
Step-by-step explanation:
The hollow spaces within the brain are known as ventricles. The ventricular system consists of four such ventricles, each playing a crucial role in the circulation of cerebrospinal fluid (CSF). Developed from the original hollow space within the neural tube, these ventricles include the lateral ventricles, the third ventricle, and the fourth ventricle. The first two, the lateral ventricles, are located deep within the cerebrum and are connected to the third ventricle through the interventricular foramina. This third ventricle exists between the left and right sides of the diencephalon, opening up into the cerebral aqueduct, which passes through the midbrain and leads to the fourth ventricle situated between the cerebellum and the brain stem. Not only do these spaces contain CSF, but they are also sites where CSF is produced by the choroid plexuses. These ventricles connect to the subarachnoid space, allowing for the flow of CSF through the ventricles and around the CNS, serving vital functions such as waste removal and providing a clear solution comprising water, small molecules, and electrolytes for the brain and spinal cord.