Variations in the intertubercular sulcus of the humerus related to handedness.

Measurements of the maximum width and depth of the intertubercular sulcus (ITS) and the angles formed by the medial and lateral walls of the ITS with the plane of its floor were recorded in 200 adult human humeri, 100 each from the right and left sides. The ITS was more often wider and its medial wall formed a more acute angle with the plane of its floor in right-sided humeri. A supratubercular ridge on the humerus was present more frequently on the right than on the left. The presence of this ridge is probably more necessary on the right to prevent medial displacement of the long head of the biceps tendon from the ITS. The greater thrust exerted by the taut tendon of the long head of the biceps in the upper limb that is used preferentially probably induces structural differences in the ITS.