Suprascapular notch harboring the two ligaments, namely superior transverse scapular ligament and anterior coracoscapular ligament is a potential site contributing in causation of suprascapular nerve entrapment syndrome. The etiological role of superior transverse scapular ligament in suprascapular nerve entrapment syndrome is established and it needs to be excised in the treatment of suprascapular nerve entrapment syndrome. The anterior coracoscapular ligament is recently introduced as a new risk factor. The mystery about the role of this ligament in suprascapular nerve entrapment syndrome attracted us to undertake morphological study of this ligament. In this study, anterior coracoscapular ligament was found as a separate fibrous band in 41.2%. According to the distal attachment of the ligament as suggested by Piyawinijwong, we found three types of anterior coracoscapular ligament: type I (52.4%), type II (40.5%) and type III (7.1%). According to the shape of ligament, we found anterior coracoscapular ligament as– Fan shaped (47.6%), band shaped (42.9%), bifid (2.4%) and vestigial type (7.1%). The mean cross sectional area of suprascapular opening with anterior coracoscapular ligament was estimated as 29.86 mm2 and without anterior coracoscapular ligament it was 29.35 mm2. The mean middle width of suprascapular opening with anterior coracoscapular ligament was 3.8 mm and without anterior coracoscapular ligament it was 4 mm. The suprascapular nerve as the only structure passing through suprascapular opening was seen in 50%. The suprascapular nerve along with suprascapular vein passing through suprascapular opening was seen in 20.6% whereas suprascapular nerve and suprascapular vessels passed through suprascapular opening in 17.6%. Accessory suprascapular veins were found in 11.8%. The anterior coracoscapular ligament apparently contributes to reduce the area of suprascapular opening leading to compression of suprascapular nerve which may cause suprascapular nerve entrapment syndrome. The anterior coracoscapular ligament if present is one of the equally important predisposing factors as superior transverse scapular ligament. Variations in morphology of anterior coracoscapular ligament may influence the area of suprascapular opening through which suprascapular nerve passes. Therefore one should not underestimate the importance of anterior coracoscapular ligament.

Keywords: Anterior coracoscapular ligament; Suprascapular nerve entrapment syndrome.