ong bones of the back of the hand.
They are attached to the wrist and to the finger bones, and may be easily
felt by pressing the fingers of one hand over the back of the other. The
metacarpal bones of the fingers have little freedom of movement, while the
thumb, unlike the others, is freely movable. We are thus enabled to bring
the thumb in opposition to each of the fingers, a matter of the highest
importance in manipulation. For this reason the loss of the thumb disables
the hand far more than the loss of either of the fingers. This very
significant opposition of the thumb to the fingers, furnishing the
complete grasp by the hand, is characteristic of the human race, and is
wanting in the hand of the ape, chimpanzee, and ourang-outang.

The phalanges, or finger bones, are the fourteen small bones arranged
in three rows to form the fingers. Each finger has three bones; each
thumb, two.

The large number of bones in the hand not only affords every variety of
movement, but offers great resistance to blows or shocks. These bones are
united by strong but flexible ligaments. The hand is thus given strength
and flexibility, and enabled to accomplish the countless movements so
necessary to our well-being.

In brief, the hand is a marvel of precise and adapted mechanism, capable
not only of performing every variety of work and of expressing many
emotions of the mind, but of executing its orders with inconceivable
rapidity.

The Bones of the Lower Limbs.

46. The Lower Limbs. The general structure and number of the bones of
the lower limbs bear a striking similarity to those of the upper limbs.
Thus the leg, like the arm, is arranged in three parts, the thigh,
the lower leg, and the foot. The thigh bone corresponds to the
humerus; the tibia and fibula to the ulna and radius; the ankle to the
wrist; and the metatarsus and the phalanges of the foot, to the metacarpus
and the phalanges of the hand.

The bones of the lower limbs may be thus arranged:

Thigh: Femur, or thigh bone,

Lower Leg:
Patella, or knee cap,
Tibia, or shin bone,
Fibula, or splint bone,

Foot:
7 Tarsal or ankle bones,
5 Metatarsal or instep bones,
14 Phalanges, or toes bones,

making 30 bones in all.

[Illustration: Fig. 22.--Right Femur, or Thigh Bone.]

47. The Thigh. The longest and strongest of all the bones is the
femur, or thigh bone. Its upper end has a rounded head which fits into the
_acetabulum_,