In mammals, the neurocranium, braincase, or brainpan (also spelled brain-pan) is the back part of the skull and houses the brain. In front of it is the interorbital region.
In humans, the neurocranium is (also) the upper portion of the skull. The other, lower part of the skull is the viscerocranium.
Evolutionarily, the human neurocranium has turned from being (just) the back part to (also) being the upper part, because during the evolutionary expansion of the brain, the neurocranium has overgrown the viscerocranium. The upper-frontmost part of the cranium also houses the evolutionarily newest part of the human brain, the frontal lobes.
The term "cranium" can be ambiguous in that it can refer to the neurocranium, or the whole skull, meaning the neurocranium and the facial skeleton.
Read more about Neurocranium: Structure, Embryonic Origins, See Also