脑室为脑内部充满脑脊液的一组腔隙结构。它延伸至脊髓形成中央管。脑室内表面覆盖有上皮状的室管膜。

脑室系统由四个脑室组成：

脑室之间的孔洞也包括在脑室系统内：

The ventricular system is a set of four interconnected cavities (ventricles) in the brain, where the cerebrospinal fluid (CSF) is produced. Within each ventricle is a region of choroid plexus, a network of ependymal cells involved in the production of CSF. The ventricular system is continuous with the central canal of the spinal cord (from the fourth ventricle) allowing for the flow of CSF to circulate. All of the ventricular system and the central canal of the spinal cord is lined with ependyma, a specialised form of epithelium.