which ventricle is located within the brain stem
This ventricle has a roof and a floor. The roof is composed of the cerebellum, located at the back of the brain, and the floor is formed by the rhomboid fossa, a depression in the brainstem. Within the floor is the facial colliculus, sulcus limitans, and the obex. Much like other portions of the ventricular system inside the brain, the fourth ventricle develops from the area inside the neural tube (the structure in an embryo that becomes the brain and spinal cord) called the central canal.