The carpometacarpal joint of the thumb is an example of which type of joint?

The carpometacarpal joint of the thumb is classified as a saddle joint due to its unique structure and the specific range of motion it allows. Saddle joints are characterized by two surfaces that are concave in one direction and convex in the other, resembling a saddle. This configuration enables a greater range of motion than most other joint types, including the ability to flex and extend, as well as abduct and adduct.

In the case of the thumb's carpometacarpal joint, this design allows for significant opposition, which is the ability to touch the thumb to the other fingers—an essential function for grasp and manipulation of objects. The saddle-shaped surfaces of the metacarpal and the trapezium bone of the wrist work together to provide this multifunctional movement.

While hinge joints allow movement in a single plane primarily for flexion and extension, and gliding joints permit limited movement between flat surfaces, these types do not enable the variety of motions that the saddle joint does. Ellipsoidal joints, like those found in the wrist, allow for movement around two axes, but they do not provide the same degree of oppositional movement that is crucial for thumb functionality. Therefore, the classification of the carpometacarpal joint of the