Although the structure of the human body has a rigid skeletal form made up of solid bones, the muscles and tendons connected to those bones allow the body to be capable of movement, permitting an infinite range of poses, postures and positions.
Viewed from the front, the positions of the adult form are evident. Leonardo da Vinci’s Vitruvian Man drawing is an earlier study of the proportions and movements of the human form.
Just as a wooden mannequin has joints that allow it to bend, the human body has flex points that allow for movement. This flexibility is performed through actions involving the joints, muscles and tendons in cooperation with the bones.
Joints are in the shoulders, hips, elbows, knees, wrists, ankles and spine.
The elbows and knees are hinge joints. The elbows allow the arms to bend forward, whereas the knees allow the legs to bend backward.
Movement is made possible for the vertebrae of the spine through glide joints.
As a figure goes from being upright to bent over, the waistline goes from horizontal to almost vertical. In the same action, the hips and upper legs shift backward in an effort to keep the figure balanced. The next pages explain more about balance and the human figure.
The shoulders and hips are ball-and-socket joints. They allow for more flexibility than elbows and knees, which have hinge joints.