A condyloid joint is one of six types of synovial joints found in the human body. Like all such joints, it is characterized by the presence of a fluid-containing joint capsule, which lubricates the surfaces of adjacent bones in the joint. The condyloid joint, however, is distinguished from the other kinds of synovial joints by the distinctive oval shape of the bones involved. Both the articular surface of the bone inserting into the joint — a surface known as a condyle — and the cavity receiving the bone are elliptical in shape.
The shape of this joint permits movement in two planes, allowing flexion and extension in one plane and adduction and abduction in another. These movements can be demonstrated by examining the wrist joint, a prime example of condyloid structure. In the wrist, or radiocarpal, joint, the condyle is located on the end of the radius bone of the forearm, and it articulates with the cavities of the adjacent carpus bones of the wrist. Bending the wrist forward toward the palm and backward toward the back of the hand represents flexion and extension, respectively, while tilting the wrist joint from side to side, as in waving one’s hand, represents abduction when tilting in the direction of the thumb and adduction when tilting in the direction of the little finger. Additionally, the wrist joint is capable of circumduction, or circling movement, through these two planes.
Another place in the body where the condyloid joint is found is in the metacarpophalangeal (MCP) joints of the hand, between the metacarpal bones in the palm and the phalangeal bones of the fingers. In this case, the articulating surfaces in the joint include the condyle of the metatarsal and the cavity of the phalange. Like the wrist joint, the MCP joints are capable of flexion, as in creating a fist, extension, as in opening the hand, abduction/adduction, as in wagging a finger from side to side, and circumduction, as in circling a finger. An exception is the MCP joint of the thumb, which has such limited movement beyond flexion and extension that it is generally considered to be a ginglymoid, or hinge, joint.
The metatarsophalangeal (MTP) joints of the foot are similar to the MCP joints. Located between the metatarsal bones of the foot and the phalangeal bones of the toes, with the elliptical condyle of the metatarsal inserting into the cavity of the phalange, the MTPs have more limited range of motion than the MCPs but perform most of the same movements. These joints permit flexion, or pointing of the toes, extension, or lifting of the toes, and abduction/abduction, or wagging the toes from side to side.