Yoshiki Kuwahara1, Takuma Yuri1, Hiromi Fujii1, Yoshiro Kiyoshige2. 1. Graduate School of Health Science, Yamagata Prefectural University of Health Science, 260 Kamiyanagi, Yamagata, 990-2212, Japan. 2. Graduate School of Health Science, Yamagata Prefectural University of Health Science, 260 Kamiyanagi, Yamagata, 990-2212, Japan. ykiyosige@yachts.ac.jp.
Abstract
PURPOSE: Although recent morphological studies have revealed that the infraspinatus muscle is subdivided, the functions of the subregions remain unknown. The aim of this study is to investigate the functions of the infraspinatus subregions during lateral rotation using real-time tissue elastography (RTE). METHODS: Ten young male volunteers participated in the study. In addition to the infraspinatus subregions, the teres minor and two of six subregions of the supraspinatus determined by Kim were examined. The muscle stiffness of these subregions was measured in six conditions during lateral rotation, i.e., at rest and during manual muscle testing (MMT) 3 contraction at 0°, 35°, and 70° of lateral rotation. RESULTS: The middle and inferior subregions of the infraspinatus, teres minor, and the posterior deep supraspinatus acted as a lateral rotator. The inferior subregion of the infraspinatus was somewhat an abductor. The superior subregion of the infraspinatus was an abductor but did not contribute to the lateral rotational motion at 35° and 70° of rotation. The anterior superficial supraspinatus played an abduction role at neutral rotation but this role gradually decreased with an increasing lateral rotational angle. CONCLUSIONS: Three subregions of the infraspinatus are functionally distinct. The superior subregion contributes to abduction, the middle subregion acts as a lateral rotator, and the inferior subregion has both functions.
PURPOSE: Although recent morphological studies have revealed that the infraspinatus muscle is subdivided, the functions of the subregions remain unknown. The aim of this study is to investigate the functions of the infraspinatus subregions during lateral rotation using real-time tissue elastography (RTE). METHODS: Ten young male volunteers participated in the study. In addition to the infraspinatus subregions, the teres minor and two of six subregions of the supraspinatus determined by Kim were examined. The muscle stiffness of these subregions was measured in six conditions during lateral rotation, i.e., at rest and during manual muscle testing (MMT) 3 contraction at 0°, 35°, and 70° of lateral rotation. RESULTS: The middle and inferior subregions of the infraspinatus, teres minor, and the posterior deep supraspinatus acted as a lateral rotator. The inferior subregion of the infraspinatus was somewhat an abductor. The superior subregion of the infraspinatus was an abductor but did not contribute to the lateral rotational motion at 35° and 70° of rotation. The anterior superficial supraspinatus played an abduction role at neutral rotation but this role gradually decreased with an increasing lateral rotational angle. CONCLUSIONS: Three subregions of the infraspinatus are functionally distinct. The superior subregion contributes to abduction, the middle subregion acts as a lateral rotator, and the inferior subregion has both functions.
Authors: Joseph E Langenderfer; Cameron Patthanacharoenphon; James E Carpenter; Richard E Hughes Journal: J Orthop Res Date: 2006-08 Impact factor: 3.494
Authors: Soo Y Kim; Erin L Boynton; Kajeandra Ravichandiran; Lillia Y Fung; Robert Bleakney; Anne M Agur Journal: Clin Anat Date: 2007-08 Impact factor: 2.414
Authors: Jeffrey J Gates; Jeremy Gilliland; Michelle H McGarry; Maxwell C Park; Daniel Acevedo; Michael J Fitzpatrick; Thay Q Lee Journal: J Orthop Res Date: 2010-01 Impact factor: 3.494