Purpose <p>This study provides an insight on the extent of muscular variability at the suprascapular notch and elaborates on its anatomical interference in suprascapular nerve arthroscopic decompression procedures.</p> Methods <p>The suprascapular notch was dissected and its muscular topography was observed in 115 cadaveric specimens. High resolution imaging of the suprascapular notch was captured by a handheld digital microscope (Q-scope). The supraspinatus and subscapularis muscles were traced as they course at the suprascapular notch vicinity. The omohyoid muscle attachment onto the suprascapular ligament was measured. A scoping review and meta-analysis were done to investigate the observed rare muscular variants.</p> Results <p>In 3.48%, the suprascapular notch anterior surface was fully covered by the subscapularis muscle. The omohyoid muscle inserted onto the suprascapular ligament in 31.25% and extended up to 3/4th of the suprascapular ligament length in 2.61%. Two rare variant muscles were encountered: subclavius posticus muscle and a newly reported “coracoscapularis muscle”.</p> Conclusions <p>Four categories of muscles with topographical relationship to the suprascapular notch and its arthroscopic feasibility have been classified: (1) constant muscles not intervening with the suprascapular notch space – supraspinatus muscle; (2) constant muscles with variable positions that can intervene with the suprascapular notch space – subscapularis muscle; (3) constant muscles with variable positions that can intervene with the surgical approach – omohyoid muscle; (4) variable muscles intervening with the suprascapular notch space and surgical approach – subclavius posticus and coracoscapularis muscles. This study elucidates the necessity to assess/secure the omohyoid muscle attachment onto the suprascapular ligament in suprascapular nerve decompression ligamentectomy.</p> Level of evidence <p>V Basic Science Research.</p>