Condyloid (ellipsoid) joint is a biaxial joint for flexion, extension, abduction, adduction, and circumduction, such as finger joints. Which option expresses this joint type?

• A. Suture
• B. Interosseous membrane
• C. Epiphyseal plate
• D. Condyloid (ellipsoid) joint

Answer: (D)

Condyloid (ellipsoid) joints are able to move in two planes, making them biaxial. They allow flexion and extension in one plane, and abduction and adduction in the perpendicular plane, with circumduction as a combined movement. This type arises from an oval convex surface articulating with a complementary concave surface, which lets the bones glide in two dimensions without true rotation around a long axis. The metacarpophalangeal joints in the fingers are a classic example, and the wrist’s radiocarpal joint is another good example. The other options describe structures that are not joints with this two‑plane mobility: sutures are immovable fibrous joints, interosseous membranes are fibrous connections between bones, and epiphyseal plates are growth regions, not functional joints.