A two-layered membrane that lines the inside of the chest and covers the surfaces of the lungs. The cavity between the two layers (known as the pleural cavity) is a potential vacuum such that, when the chest wall expands with breathing, the lungs are forced to do so as well, thereby drawing air into them. The pleural cavity is sometimes used by neurosurgeons as a potential receptacle for receiving This clear, water-like fluid forms, for the most part, within the brain, more specifically inside the ventricles of the ... from the The brain is not an entirely solid organ. There are chambers within the brain, referred to as ventricles or, more correc... of the brain, or for receiving fluid from a A cavity, within the spinal cord, which is filled with cerebrospinal fluid. Syringomyelia cavities come in various “sh... cavity.