Potential excursion and relative tension of muscles in the shoulder girdle: Relevance to tendon transfers

Muscles used for transfer ought to have adequate structural properties. The purpose of this study was to provide a database of potential excursion (muscle excursion without reference to connective tissue restraints) and relative tension (muscle physiologic cross-sectional area in percentage among a group) in shoulder girdle muscles. Thirteen muscles in 13 human cadavers aged 17 to 89 years at death were studied. Potential excursion ranged from 6.7 cm (supraspinatus) to 33.9 cm (latissimus dorsi). Relative tension ranged from 1.7% (levator scapulae) to 20.9% (deltoid). Significant discrepancies were found between the properties of some of the muscles used as transfers around the shoulder and the properties of the muscles for which they are commonly used as substitutes. Despite the limitations of cadaveric studies and the fact that many other factors are involved in muscle transfers, this database of structural properties of shoulder girdle muscles may help when planning tendon transfers around the shoulder.