著者

木戸 忠人 井樋 栄二 今野 則和 佐野 晃久 浦山 雅和

出版者

Japan Shoulder Society

雑誌

肩関節 (ISSN:09104461)

巻号頁・発行日

vol.22, no.2, pp.169-172, 1998

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The purpose of this study was to determine the in vivo function of the biceps as an active depressor of the humeral head. Thirty-eight shoulders were examined: 19 shoulders with rotator cuff tears (RCT, avg age 59 yrs) and 19 shoulders with normal MRI findings of the rotator cuff (Control, avg age 55yrs). A special arm brace which was fixed to the upper arm was used to keep the biceps in active contraction (biceps loading) during arm elevation. The subjects were asked to grasp a rubber band attached to the distal end of the brace, pull it proximally, and keep the elbow flexed against the resistant force producted by the band. The x-ray were obtained with the arm elevated at 0,45,90 degrees in the scapular plane with and without pulling the band. The center of the humeral head was determined using NTH image and compared between the groups with and without biceps loading. Without biceps loading, the positions of the humeral head at 0,45 degrees were significantly higher in RCT than those in Control (p=0.0101, p=0.0020, respectively). After loading the biceps, the humeral head was depressed significantly at each degree in RCT (P=0.0082, p=0.0259, p=0.0059, respectively). As a result of biceps loading, there were no more significant differences in the positions of the humeral head between RCT and Control (p=0.3285). The positions of the humeral head in RCT with biceps loading were similar to the positions in Control without biceps loading. This is the first study to show the in vivo function of the biceps as an active depressor. From these results, we conclude that the biceps is an active depressor of the humeral head in cuff-defficient shoulders.

著者

皆川 洋至 井樋 栄二 佐藤 毅 今野 則和 本郷 道生 佐藤 光三

出版者

日本肩関節学会

雑誌

肩関節 (ISSN:09104461)

巻号頁・発行日

vol.20, no.1, pp.103-109, 1996-10-15 (Released:2012-11-20)

参考文献数

14

被引用文献数

3

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Each muscle of the rotator cuff is known to have several intramuscular tendons which provide attachment to numerous muscle fiders. The anatomical relationship between intramuscular and extramuscular tendons needs to be determined to know the distribution of the force to the rotator cuff tendon. The purpose of this study was to clarify the morphology of the transitional zone of intramuscular to extramuscular tendons of the rotator cuff.The muscle fibers of cuff muscles of 20 embalmed shoulders without full-thickness rotator cuff tears were removed to examine the transitional zone of the intramuscular to extramuscular tendons macroscopically. Histological sections of the musculotendinous junction were perpared to evaluate the transitional forms microscopically.We defined the intramuscular tendon as the tendon inside the muscle belly and the extramuscular tendon as the tendon outside the muscle. The extramuscular tendons from the rotator cuff tendon distally. Location was expressed as the % position of the anterior and posterior margins of the musculotendinous junction. The intramuscular tendons of the infraspinatus, teres minor, and subscapularis were contiguous to the whole extramuscular tendons and that the supraspinatus was located in the anterior one-third of the extramuscular tendon(0±0% to 28±15%). Microscopically, the intramuscular tendon of the supraspinatus formed a tendon fiber bundle and was continuous with the second of five layers of the extramuscular tendon (Clark and Harryman,1992).Conclusion: The connection of intramuscular tendon to extramuscular tendon was specific to each cuff muscle. The intramuscular tendon of the supraspinatus was attached to the anterior one-third of the extramuscular tendon and was contiguous to the second layer.