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. Author manuscript; available in PMC: 2014 Feb 1.
Published in final edited form as: J Hand Surg Am. 2013 Jan 5;38(2):241–249. doi: 10.1016/j.jhsa.2012.11.007

Figure 4. Mean joint moments generated by muscles crossing the shoulder during simulated abduction, shoulder extension, and external rotation movements.

Figure 4

The 3 simulated movements are labeled at the top of the figure. Mean joint moments were computed in 6 possible directions of shoulder movement, which are labeled for each simulated movement. Positive joint moments were generated in the direction of abduction, shoulder flexion, and internal rotation. Negative joint moments were generated in the direction of adduction, shoulder extension, and external rotation. Some muscles generated joint moments in both agonist and antagonist directions (e.g. abduction and adduction), indicating that their moment arms changed direction during the simulations. For each direction of shoulder movement, the combined mean joint moments of both the posterior deltoid and teres minor as a percentage of the total mean joint moment are indicated on the figure. The posterior deltoid contributed to abduction, adduction, shoulder extension, and external rotation joint moments, and the teres minor contributed to adduction, shoulder extension, and external rotation joint moments.