brain ventricle morphology trait fourth ventricle morphology trait Any measurable or observable characteristic related to the shape, structure, color, or pattern of the irregularly shaped cavity in the rhombencephalon, between the medulla oblongata, the pons, and the isthmus in front, and the cerebellum behind; it is continuous with the central canal of the cord below and with the cerebral aqueduct above, and through its lateral and median apertures it communicates with the subarachnoid space. Trait.ontology VT:0000828 ventricle of rhombencephalon morphology trait ventriculus quartus morphology trait hindbrain morphology trait