Which structure is considered a valgus stabilizer of the elbow?

The ulnar collateral ligament is recognized as a valgus stabilizer of the elbow due to its essential role in maintaining the joint's stability against a valgus stress, which typically occurs when a force is applied to the lateral side of the elbow. Valgus stress can result in excessive gapping on the medial side of the joint, making the integrity of the ulnar collateral ligament critical in preventing injury and ensuring proper function of the elbow during activities that involve throwing or overhead movements.

In contrast, the radial collateral ligament primarily provides stability against varus forces, which act from the medial side of the joint, while the transverse ligament does not play a significant role in stabilizing the elbow joint in response to valgus stress. The interosseous membrane, though important for transmitting forces between the radius and ulna, is not directly involved in stabilizing the elbow against valgus forces. Thus, the ulnar collateral ligament is the key structure that provides the necessary support to withstand valgus pressures on the elbow joint.