What is the function of the anterior coracoscapular ligament?–A morphological study on the newest potential risk factor for suprascapular nerve entrapment

Abstract

The suprascapular notch (SSN) is the most common site of suprascapular nerve neuropathy, which may be brought on by the presence of a deep, narrow SSN and structures restricting the space for the nerve. The anterior coracoscapular ligament (ACSL) is a fibrous band extending on the anterior side of the suprascapular notch. As it may tighten the osteo-fibrous tunnel for the nerve, it has been proposed as a new anatomical risk factor in its entrapment. However, this structure occurs in up to 60% of patients, many of whom do not demonstrate any nerve injury. The aim of this work is to evaluate the association between the occurrence of the ACSL and SSN morphology. The suprascapular notch region was dissected in 100 formalin-fixed, cadaveric shoulders. The ACSL (if present) and the SSN were assigned to a classification based on their morphology and diameters. Statistical analysis was performed. The ACSL was present in 52 scapulae (52%) and in all cases, the suprascapular nerve travelled superior to the ACSL. Mechanically relevant types of ACSL were found to occur significantly more often when deeper notches were present (p=0.0018). The mechanically efficient ACSL is more common in deep and narrow SSNs, which are associated with suprascapular nerve neuropathy. Thus, by supporting the nerve, the ACSL can protect against its injury.