ABSTRACT

The soft, live brain is supported by the three meninges, pia, arachnoid (1) and dura mater, as well as the cerebrospinal fluid (CSF) in the subarachnoid space. The brain is divided into left and right hemispheres. Each has a ventricle (2) that extends from the parietal (3) into the frontal (4), occipital (5) and temporal (6) lobes. These lateral ventricles communicate with the third ventricle (7) that lies between the two hemispheres. The third ventricle leads to the fourth via the narrow cerebral aqueduct (8). Vascular choroid plexuses produce CSF, which is exported via foramina in the fourth ventricle (9) to fill the subarachnoid space. In the newborn, obstruction of the normal flow of CSF causes hydrocephaly.