USA Biology Olympiad (USABO) Practice Exam

What type of joints are examples of hinge joints found in the body?

1. Shoulder joints

2. Knee joints

3. Hip joints

4. Wrist joints

The correct answer is: Knee joints

Hinge joints are specialized types of synovial joints that allow motion predominantly in one plane, enabling flexion and extension. The knee joint is a prime example of a hinge joint, as it primarily allows for bending and straightening of the leg. This structure provides a stable connection between the thigh bone (femur) and the shin bone (tibia), enabling efficient movement during walking, running, and jumping. In contrast, the shoulder and hip joints are ball-and-socket joints, which allow for a greater range of motion in multiple directions. The wrist joint, while it does allow for some bending and straightening, is classified as a complex joint including various types of movements and is not limited to the uniaxial movement seen in hinge joints. Thus, the knee joint exemplifies the characteristics of hinge joints due to its specific functional design allowing for the primary movement of flexion and extension.