llar bones,
and two scapulae, or shoulder blades. The clavicle on either side connects
with the upper end of the sternum and serves as a _brace_ for the
shoulder, while the scapula forms a socket for the humerus (the large bone
of the arm) and supplies many places for the attachment of muscles.

The _pelvic girdle_ consists of two large bones of irregular shape, called
the _innominate_ bones. They connect behind with the sacrum and in front
they connect, through a small pad of cartilage, with each other. On the
inside of the girdle is a smooth, basin-shaped support for the contents of
the abdomen, but on the outside the bones are rough and irregular and
provide many places for the attachment of muscles and ligaments. Each
innominate bone has a deep, round socket into which the end of the femur
(the long bone of the leg) accurately fits.

5. _The Arm and Hand Groups._--A long bone, the _humerus_, connects the arm
with the shoulder and gives form to the upper arm. In the forearm are two
bones, the _radius_ and the _ulna_, which connect at one end with the
humerus and at the other with the bones of the wrist (Fig. 102).

[Fig. 102]

Fig. 102--*Bone groups of arm and leg.*

A group of eight small, round bones is found in the wrist, known as the
_carpal_ bones. These are arranged in two rows and are movable upon one
another. Five straight bones, the _metacarpals_, connect with the wrist
bones and form the framework for the palm of the hand. Attached to the
metacarpals are the bones of the fingers and thumb. These form an
interesting group of fourteen bones, called the _phalanges of the fingers_
(Fig. 102).

The bones of the hand provide a mechanical device, or machine, for
grasping, and the arm serves as a device for moving this grasping machine
from place to place. The work of the arm, in this respect, is not unlike
that of a revolving crane upon the end of which is a grab-hook. The hand
without the arm to move it about would be of little use.

6. _The Leg and Foot Groups._--These correspond in form and arrangement to
the bones of the arm and hand. Since, however, the leg and foot are used
for purposes different from those of the arm and hand, certain differences
in structure are to be found. The _patella_, or kneepan, has no
corresponding bone in the arm; and the _carpus_, or ankle, which
corresponds to the wrist, contains seven instead of eight bones. The bones