Development of the Nervous System Quiz

See Formation of the Nervous System. Option B is correct. When the front end of the neural tube closes, it swells into three primary brain vesicles, which are fluid-filled dilations (swellings) of the tube. They are the prosencephalon (forebrain), the mesencephalon (midbrain) and the rhombencephalon (hindbrain). The Latin names are the formal terms and the English names are the usual way of saying the same thing. A little later the forebrain divides into the telencephalon and the diencephalon, and the hindbrain divides into the metencephalon and the myelencephalon, while the midbrain stays as it is. That gives five secondary brain vesicles. The telencephalon goes on to form the cerebral hemispheres (the cerebrum), the diencephalon includes the thalamus and hypothalamus, and the hindbrain derivatives include the pons, cerebellum and medulla. So the sequence to remember is "three, then five": three primary vesicles split into five secondary vesicles, and the exam trap is to mix the two sets, or to list adult structures instead of embryonic vesicles.

• Primary vesicles: three: forebrain, midbrain and hindbrain
• Secondary vesicles: five, as the forebrain and hindbrain divide and the midbrain stays whole
• Trap: do not mix up the two sets