Fourth Ventricle

**Definition:** An irregularly shaped cavity in the RHOMBENCEPHALON, located 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.

**Tree numbers:** - A08.186.211.140.500

**Synonyms:** - 4th Ventricle - Quarto Ventricolo