What structure is stressed when testing a patient’s elbow to resist a Valgus force?

When testing a patient's elbow to resist a valgus force, the structure that is primarily stressed is the medial collateral ligament. A valgus force occurs when an external force pushes the distal segment of a joint away from the midline of the body, in this case, applying pressure on the lateral side of the elbow. The medial collateral ligament is responsible for stabilizing the inner aspect of the elbow against such forces. It acts to prevent excessive movement, particularly abduction at the elbow joint, making it essential for the integrity and proper function of the joint during activities that require stability and precision.

While other structures like the lateral collateral ligament and the ulnar nerve are associated with the elbow, they are not the primary structures involved when a valgus force is applied. The radial collateral ligament, located on the lateral side of the elbow, supports against varus forces but is not directly implicated in resisting valgus stress. Therefore, when the elbow is subjected to this type of force, the medial collateral ligament is significantly engaged, highlighting its role in maintaining joint stability.