Origin of the long head of biceps brachii from the supraglenoid tubercle and glenoid labrum

The long head of the biceps tendon (LHBT) provides stability to the glenohumeral joint. Although it has been observed to arise from the supraglenoid tubercle and glenoid labrum, its mode of attachment to the glenoid labrum is variable. This study therefore aimed to (i) identify the origin of the LHBT, and (ii) investigate if there are differences in attachment related to age, gender and side. A total of 140 shoulders from 30 male and 40 female cadavers were examined: the glenoid fossa with the glenoid labrum and LHBT attached were exposed. The classification of Vangsness et al. (1994) was adopted to determine the mode of attachment of the LHBT. Gender, age, side and type of attachment were double-entered into the Statistical Package for Social Sciences. Chi square tests were conducted to determine statistical significance, which was set at P<0.05. Type I was the most common attachment (47.7%) of the LHBT, then Type II (31.5%), Type III (16.2%) and Type IV (4.6%). No significant difference was observed between the type of attachment of the LHBT and sex, side or age. The LHBT consistently arose from the glenoid labrum and supraglenoid tubercle in all the specimens, with the majority of tendons having a posterior orientation. Involvement of the glenoid labrum can be associated with injury to the LHBT: this may explain the existence of a combined injury in shoulder joint instability. Further study is needed to investigate the association between variations of the LHBT attachment to the glenoid labrum and shoulder joint stability.