Based on the orientation and proportion of the fibers that attach on
the glenoid labrum (anterior to posterior) the long head of biceps can be classified as type I through IV (I type describing a more posterior attachment, IV describing a more anterior attachment, and II, III being mixed).
In contrast, large - scale cadaver studies (Vangness et al., 1994) describe the origin of the long head attaching quite evenly between the supraglenoid tubercle and the superior
glenoid labrum, between 40 - 60 % of the fibers attaching to the supraglenoid tubercle.