The lowest positioned of the four cerebral The brain is not an entirely solid organ. There are chambers within the brain, referred to as ventricles or, more correctly, cerebral ventricles, to distinguish them from the ventricles of the heart. They represent the remnants of the central canal of the developing central nervous system, although they have taken on a much more complex shape than the original embryonic structure. There are four in total, one each side of the midline (referred to as the lateral ventricles) and two more, in the midline, referred to as the third and fourth ventricles, albeit often using Roman numerals.. It lies in the That part of the cranial cavity that lies below the tentorium and which contains the brain stem and the cerebellum. but may become partly displaced into the top of the The individual bones that comprise the spinal column are made up of a weight-bearing “body” and other components which, together, form a ring of bone, behind the body. These individual vertebrae, joined together as the spinal column, therefore, create a canal running down the entire length of the spine. in Chiari type 2 malformations.