The purpose of this study was to reveal the detailed layered structure of the rotator cuff with regard to the coraocuhumeral ligament by dissecting anatomical specimens of adult shoulders. 53 shoulders of 39 adult cadavers were used for this study. After resecting the acromion, the connective tissue was carefully removed and the layered structure of the rotator cuff on the superior portion of the greater tuberosity was observed macroscopically. The connective tissue between the posterior edge of the coracoid process and the rotator interval, which was not a ligamentous tissues, was observed and then recognized as the coracohumeral ligament by its pathway. The coracohumeral ligament splayed out the supraspinatus and infraspoinatus tendon. After removing both tendons, the coracohumeral ligament was observed to fuse with underlying capsule and extended to the greater tuberosity. However in 20 out of 53 specimens, the superficial distribution of the coracohumeral ligament was restricted to the narrow region. In 11 out of 20 specimens, the pectoralis minor tendon unusually ran beyond the coracoid process and disturbed the development of the coracohumeral ligament. In the other 9 specimens, the supraspinatus tendon was unusually inserted to the lesser tuberosity and interrupted the development of the coracohumeral ligament. This result suggested that the layered structure of the rotator cuff with regard to the coracohumeral ligament was affected by the insertion pattern of the supraspinatus tendon and the pectoralis minor tendon.
