Which bone is directly involved in the articulation of the stifle joint?

The tibia is directly involved in the articulation of the stifle joint, which is the equivalent of the knee joint in humans. The stifle joint is formed by the femur (the thigh bone) and it articulates with both the tibia and the patella (kneecap). The tibia plays a crucial role in this joint as it supports the weight of the body during movement and serves as the primary bone in the leg beneath the stifle joint.

In contrast, the scapula is a flat bone that forms part of the shoulder joint and is not connected to the stifle. The radius is one of the two long bones in the forelimb, specifically in the forearm of animals, and does not have any connection to the hindlimb or the stifle joint. The clavicle, or collarbone, is also part of the shoulder complex and does not contribute to the formation of the stifle joint. Thus, the tibia is the only bone listed that directly participates in the structure and function of the stifle joint.