Skull, skeletal framework of the head
of vertebrates, composed of bones
or cartilage, which form a unit
that protects the brain and
some sense organs. The upper jaw,
but not the lower, is part of the skull.
The human cranium, the part that
contains the brain, is globular
and relatively large in comparison
with the face. In most other animals
the ****** portion of the skull,
including the upper teeth and the nose,
is larger than the cranium.
In humans the skull is supported
by the highest vertebra, called the atlas,
permitting nodding motion.
The atlas turns on the next-lower
vertebra, the axis, to allow
for side-to-side motion.