ones are five in number. They articulate at one
extremity with one range of tarsal bones; at the other extremity, with
the first range of the toe-bones.

[Illustration: Fig. 19. A representation of the upper surface of the
bones of the foot. 1, The surface of the astragulus, where it unites with
the tibia. 2, The body of the astragulus. 3, The calcis, (heel-bone.) 4,
The scaphoid bone. 5, 6, 7, The cuneiform bones. 8, The cuboid. 9, 9, 9,
The metatarsal bones. 10, The first bone of the great toe. 11, The second
bone. 12, 13, 14, Three ranges of bones, forming the small toes]

[Illustration: Fig. 20. A side view of the bones of the foot, showing its
arched form. The arch rests upon the _heel_ behind, and the _ball_ of the
toes in front. 1, The lower part of the tibia. 2, 3, 4, 5, Bones of the
tarsus. 6, The metatarsal bone. 7, 8, The bones of the great toe. These
bones are so united as to secure a great degree of elasticity, or spring.]

_Observation._ The tarsal and metatarsal bones are united so as to
give the foot an arched form, convex above, and concave below. This
structure conduces to the elasticity of the step, and the weight of
the body is transmitted to the ground by the spring of the arch, in a
manner which prevents injury to the numerous organs.

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111. Describe the metatarsal bones. Explain fig. 19. What is
represented by fig. 20? What is said of the arrangement of the bones
of the foot?

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112. The PHALANGES (fig. 19) are composed of fourteen bones; each of
the small toes has three ranges of bones, while the great toe has but
two.

113. The JOINTS form an interesting part of the body. In their
construction, every thing shows the regard that has been paid to the
security and the facility of motion of the parts thus connected
together. They are composed of the extremities of two or more
bones, _Car'ti-lages_, (gristles,) _Syn-o'vi-al_ membrane, and
_Lig'a-ments_.

[Illustration: Fig. 21 The relative position of the bones, cartilages,
and synovial membrane. 1, 1, The extremities of two bones that concur to
form a joint. 2, 2, The cartilages that cover the end of the bones. 3, 3,
3, 3, The synovial membrane which covers the cartilage of both bones, and
is then doubled back from one to the other; it is represented by the
dotted lines.]

[Illustration: Fig. 22. A vertical section of the knee-joint. 1, The
femur. 3, The patella. 5, The tibia. 2, 4, T