[Illustration: Fig. 16.
1. Portions of the backbone. 2. Cranial
bones. _4_. Breast-bone. _5_. Ribs. _7_. Collar-bone.
_8_. Arm-bone (humerus). _9_. Shoulder-joint.
_10, 11_. Bones of the fore-arm (ulna and
radius). _12_. Elbow-joint. _13_. Wrist-joint. _14_.
Bones of the hand. _15, 16_. Pelvic bones. _17_.
Hip-joint. _18_. Femur. _19, 20_. Bones of the
knee-joint. _21, 22_. Fibula and tibia. _23_. Ankle
bone. _24_. Bones of the foot.]

THE BONES OF THE UPPER EXTREMITIES are sixty-four in number, and are
classified as follows: The Scapula, Clavicle, Humerus, Ulna, Radius,
Carpus, Metacarpus, and Phalanges. The _Scapula_, or shoulder-blade, is
an irregular, thin, triangular bone, situated at the posterior part of
the shoulder, and attached to the upper and back part of the chest. The
_Clavicle_, or collar-bone, is located at the upper part of the chest,
between the sternum and scapula, and connects with both. Its form
resembles that of the italic letter _f_, and it prevents the arms from
sliding forward. The _Humerus_, the first bone of the arm, is long,
cylindrical, and situated between the scapula and fore-arm. The _Ulna_
is nearly parallel with the radius, and situated on the inner side of
the fore-arm. It is the longer and larger of the two bones, and in its
articulation with the humerus, forms a perfect hinge-joint. The
_Radius_, so called from its resemblance to a spoke, is on the outer
side of the fore-arm, and articulates with the bones of the wrist,
forming a joint. The ulna and radius also articulate with each other at
their extremities. The _Carpus_, or wrist, consists of eight bones,
arranged in two rows. The _Metacarpus_, or palm of the hand, is composed
of five bones situated between the carpus and fingers. The _Phalanges_,