What type of joint is the metatarsophalangeal joint (MPJ)?

• A. Saddle joint
• B. Ball and socket joint
• C. Hinge joint
• D. Condyloid joint

Answer: (D)

The metatarsophalangeal joint (MPJ) is classified as a condyloid joint. This type of joint allows for movement in two planes: flexion-extension and abduction-adduction. In the case of the MPJ, it permits the toe to move up and down (flex and extend) as well as side to side (abduct and adduct) to some extent, which is vital for walking, running, and maintaining balance.

The structure of the MPJ features an oval-shaped condyle from the metatarsal that fits into a socket formed by the proximal phalanx. This design facilitates the varied range of motion needed at the toes while providing stability during weight-bearing activities. The presence of ligaments and a joint capsule also aids in supporting the joint and allowing for healthy articulation.

Other joint types mentioned do not accurately describe the MPJ's capabilities or structural anatomy. A saddle joint would allow for greater range of movement in different directions, particularly opposition, which is not a function of the MPJ. A ball and socket joint would provide a much wider range of motion, characteristic of the hip or shoulder joints, which again is not applicable here. Hinge joints primarily allow motion in one plane, such as