s.
6 False Ribs.
4 Floating Ribs.

III. Sternum.

IV. Two Hip Bones.

V. Hyoid Bone.

37. The Spinal Column. The spinal column, or backbone, is a
marvelous piece of mechanism, combining offices which nothing short of
perfection in adaptation and arrangement could enable it to perform. It is
the central structure to which all the other parts of the skeleton are
adapted. It consists of numerous separate bones, called vertebrae. The
seven upper ones belong to the neck, and are called cervical
vertebrae. The next twelve are the dorsal vertebrae; these belong to
the back and support the ribs. The remaining five belong to the loins, and
are called lumbar vertebrae. On looking at the diagram of the backbone
(Fig. 9) it will be seen that the vertebrae increase in size and strength
downward, because of the greater burden they have to bear, thus clearly
indicating that an erect position is the one natural to man.

[Illustration: Fig. 16.--The Spinal Column.]

This column supports the head, encloses and protects the spinal cord, and
forms the basis for the attachment of many muscles, especially those which
maintain the body in an erect position. Each vertebra has an opening
through its center, and the separate bones so rest, one upon another, that
these openings form a continuous canal from the head to the lower part of
the spine. The great nerve, known as the spinal cord, extends from
the cranium through the entire length of this canal. All along the spinal
column, and between each two adjoining bones, are openings on each side,
through which nerves pass out to be distributed to various parts of the
body.

Between the vertebrae are pads or cushions of cartilage. These act as
"buffers," and serve to give the spine strength and elasticity and to
prevent friction of one bone on another. Each vertebra consists of a body,
the solid central portion, and a number of projections called processes.
Those which spring from the posterior of each arch are the spinous
processes. In the dorsal region they are plainly seen and felt in thin
persons.

The bones of the spinal column are arranged in three slight and graceful
curves. These curves not only give beauty and strength to the bony
framework of the body, but also assist in the formation of cavities for
important internal organs. This arrangement of elastic pads between the
vertebrae supplies the spine with so many elastic springs, which serve to
break the effect