CHAPTER XVIII.

OUR BONES AND THEIR USES.


~1. The Bones.~--In an earlier chapter we learned something about the
bones. This we must try to recall. You will remember that we called the
bones the framework of the body, just as the timbers which are first put
up in building a house are called its frame.

~2. The Skeleton.~--All the bones together make up the _skeleton_. (See
page 95.) There are about two hundred bones in all. They are of many
different shapes. They vary in size from the little bones of the ear,
which are the smallest, to the upper bone of the leg, which is the
largest in the body.

~3.~ The skeleton is divided into four parts: the _skull_, the _trunk_,
the _arms_, and the _legs_. We must learn something more about the bones
of each part.

~4. The Skull.~--The _skull_ is somewhat like a shell. It is made of a
number of bones joined together in such a way as to leave a hollow place
inside to hold the brain. The front part of the skull forms the
framework of the face and the jaws. In each ear there are three curious
little bones, which aid us in hearing.

~5. The Trunk.~--The bones of the trunk are, the _ribs_, the