What ligament is stressed during the Yergason's and Speed's tests?

The transverse humeral ligament is stressed during the Yergason's and Speed's tests because both of these assessments specifically evaluate the stability of the long head of the biceps brachii tendon, which runs through the bicipital groove of the humerus. The transverse humeral ligament serves to hold the biceps tendon securely within this groove.

In Yergason's test, the action of resisting supination and external rotation places tension on the biceps tendon, along with the associated ligaments that provide stability. Similarly, Speed's test involves resisting shoulder flexion against resistance, which also engages the biceps tendon and makes the transverse ligament critical in assessing its stability and integrity.

The focus here is on testing the functionality and integrity of the structures that support the long head of the biceps, where the transverse humeral ligament plays a crucial role in maintaining proper positioning of the tendon inside the bicipital groove.