Which joints are classified as ball and socket joints?

Ball and socket joints are characterized by a spherical end of one bone fitting into a cup-like cavity of another bone, allowing for a wide range of motion in multiple directions. The shoulder and hip joints exemplify this type of joint structure.

In the shoulder joint, the head of the humerus (the upper arm bone) fits into the shallow glenoid cavity of the scapula (shoulder blade), providing the ability to move the arm in various directions, including rotation. Similarly, the hip joint features the ball-shaped head of the femur (the thigh bone) fitting into the deep socket of the acetabulum in the pelvis, enabling movements like walking, running, and bending at the waist.

Knowing the function and structure of ball and socket joints helps in understanding their significant role in providing flexibility and mobility throughout the body. Other joint types, such as hinge joints (like the elbow and knee), offer different ranges of movement, mainly limited to flexion and extension, whereas the wrist and ankle joints are classified as more complex structures that incorporate various joint types rather than fitting the definition of ball and socket joints.