Laboratory for Kinematics and Neuromechanics, Department of Orthopaedics and Rehabilitation Medicine, Leiden University Medical Center, Postzone B0-Q, Postbus 9600, 2300 RC Leiden, The Netherlands; Department of Orthopaedics, Leiden University Medical Center, Postzone J11R, Postbus 9600, 2300 RC Leiden, The Netherlands.
Faculty of Human Movement Sciences, VU University of Amsterdam, Van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands.
Hum Mov Sci. 2014 Feb;33:273-83. doi: 10.1016/j.humov.2013.08.010. Epub 2013 Nov 28.
The debate on the clinical and functional role of the Supraspinatus in relation to the Deltoid necessitates experimental assessment of their contributions to arm elevation. Our goal was to evaluate the responses of both muscles to increased elevation moment loading.
Twenty-three healthy volunteers applied 30N elevation forces at the proximal and distal humerus, resulting in small and large glenohumeral elevation moment tasks. The responses of the Deltoid and Supraspinatus were recorded with surface and fine-wire electromyography, quantified by (EMGdistal-EMGproximal), and normalized by the summed activations (EMGdistal+EMGproximal) to RMuscle ratios.
Deltoid activity increased with large elevation moment loading (RDE=.11, 95%-CI [.06-.16]). Surprisingly, there was no significant average increase in Supraspinatus activation (RSSp=.06, 95%-CI [-.08 to .20]) and its response was significantly more variable (Levene's test, F=11.7, p<.001). There was an inverse association between the responses (ß=-1.02, 95%-CI [-2.37 to .32]), indicating a potential complementary function of the Supraspinatus to the Deltoid.
The Deltoid contributes to the glenohumeral elevation moment, but the contribution of the Supraspinatus is variable. We speculate there is inter-individual or intra-muscular function variability for the Supraspinatus, which may be related to the frequently reported variations in symptoms and treatment outcome of Supraspinatus pathologies.
关于冈上肌与三角肌在临床和功能上的关系一直存在争议，这需要对它们在肩部抬高过程中的贡献进行实验评估。我们的目标是评估这两块肌肉对肩部抬高力矩增加的反应。
23 名健康志愿者在肱骨近端和远端施加 30N 的提升力，产生小和大的盂肱关节提升力矩任务。三角肌和冈上肌的反应通过表面和细针肌电图记录，通过（EMG 远端-EMG 近端）进行量化，并通过（EMG 远端+EMG 近端）与 RMuscle 比值进行归一化。
三角肌的活动随着大的提升力矩负荷而增加（RDE=.11，95%CI [.06-.16]）。令人惊讶的是，冈上肌的激活并没有显著增加（RSSp=.06，95%CI [-.08 至.20]），而且其反应的变异性明显更大（Levene 检验，F=11.7，p<.001）。两者的反应之间存在负相关（ß=-1.02，95%CI [-2.37 至.32]），表明冈上肌与三角肌可能具有互补功能。
三角肌对盂肱关节提升力矩有贡献，但冈上肌的贡献是可变的。我们推测冈上肌存在个体间或肌内功能的变异性，这可能与冈上肌病变的症状和治疗结果经常出现变化有关。
