Muscles variations with topographical relationship to the suprascapular notch and its potential arthroscopic...

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.

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.

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".

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.

V Basic Science Research.