'Superior biceps aponeurosis'-Morphological characteristics of the origin of the short head of the biceps brachii muscle.

PURPOSE: Our aim was to characterize the morphology of the proximal attachment of the biceps brachii short head. We hypothesize that it has an aponeurotic component that may affect shoulder joint biomechanics. METHODS: The coracoacromial region and the biceps brachii muscle were dissected in 30 cadaveric shoulders. The course and dimensions of the tendon and aponeurosis were evaluated. The cross-sectional area of the belly of the short head and the length of the whole muscle were measured. Correlations between the aponeurosis and dimensions of the muscle were tested with the Spearman's rank correlation coefficient. RESULTS: Aponeurosis was present in all specimens, although in 10 cases it was vestigial. The aponeurotic part of the muscle (mean length 90.7 ± 16.3 mm, mean width 12.5 ± 2.9 mm) branched off laterally and traveled to the acromion, blending with the coracoacromial ligament creating the aponeurotic membrane. We named this structure the "superior biceps aponeurosis". The mean length of the biceps brachii was 31.3 ± 2.1 cm and the mean cross-sectional area of the short head was 210.7 ± 54.3 mm2. The dimensions of the "superior biceps aponeurosis" correlated positively with the cross-sectional area of the muscle (R2 from 0.37 to 0.52, p from 0.014 to 0.001). CONCLUSION: The origin of the short head of the biceps brachii muscle has a varied aponeurotic component combining the aponeurotic part of the muscle and the aponeurotic membrane. Together, they create the "superior biceps aponeurosis". CLINICAL RELEVANCE: The morphology of the origin of the biceps brachii short head is relevant in Bristow/Latarjet procedures. This aponeurotic component may affect the shoulder joint biomechanics after the coracoid process transfer.

"Pseudo-suprascapular notch": is it a sonographic trap in suprascapular nerve block?

BACKGROUND AND OBJECTIVES: The aim of the study was to describe the radiological anatomy of the pseudo-suprascapular notch-a structure localized at the floor of the supraspinatus fossa, just below the true suprascapular notch. In sonographic examination, it may imitate the suprascapular notch leading to misidentification of these structures. METHODS: Ultrasound assessment of the suprascapular notch region was performed in 100 patients who underwent chest CT due to other indications. The presence of the suprascapular notch and the pseudo-suprascapular notch was evaluated together with their maximal width and depth using both techniques. The correlation between the dimensions of these two notches was assessed. RESULTS: The pseudo-suprascapular notch was recognized in 82 patients. In four of them the suprascapular notch could not be visualized in ultrasound due to obscuring clavicle. In all cases the pseudo-suprascapular notch contained a small artery. In comparison to the suprascapular notch, the pseudo-suprascapular notch was significantly narrower and shallower, except for 10 cases with vestigial suprascapular notch where the pseudo-suprascapular notch was the only hollow in this region. The dimensions of both structures did not correlate with each other. Finally, the pseudo-suprascapular notch did not present any significant asymmetry (p=0.1185) or sexual dimorphism (43 women vs 38 men, p=0.2025). CONCLUSIONS: The pseudo-suprascapular notch is a hollow for nutrient vessels that can be mistaken for the regular suprascapular notch in cases of difficult sonographic navigation.