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Hinge Joints
Hinge joints are simple but important joints in your body. A hinge
joint works like the hinge of a door. It allows movement in only one
direction. Hinge joints allow your legs, arms, and fingers to bend and
straighten.
Hinge joints are found
at the knees, elbows,
fingers, and toes. The knee
joint is the largest hinge
joint in the human body.
It “locks” when you stand
straight. The knee joint’s
locking action makes it
easier for you to stand for
long periods of time.
Ball-and-Socket Joints
Ball-and-socket joints allow bones to swivel in nearly any direction.
Ball-and-socket joints get their name from the shapes of the two bones
that meet there. One example is the shoulder joint. The ball of the upper
arm bone fits snugly into the hollow socket of the shoulder.
Ball-and-socket joints are found at the shoulder and hip. The hip is
the strongest of all joints. It must be strong to support the weight of
the upper body. It is not quite as flexible as the shoulder joint. You can
swing your arm in a complete circle.
Hinge joints
allow your
knees to bend.
Ball-and-
socket joints
allow you to
swivel your
shoulders
and hips.
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