Teres major muscle – insertion footprint

Teres major muscle (TM) and latissimus dorsi muscle (LD) are frequently used in muscle transfers around the shoulder girdle. Some authors have suggested harvesting techniques in which the muscle is detached in continuity with a bone segment. Information on the bony attachment footprint of these muscles is lacking. The purpose of this study was to investigate the region of attachment of the TM to facilitate safe and complete harvesting with a bone segment where it is indicated, and to determine the relationship of the TM footprint with that of the LD. Twenty-eight upper extremities of 14 human cadavers (six female, eight male) were investigated during the students' dissection course in the winter term 2012. The attachment footprints were photographed and the images were processed with ImageJ Version 1.46r. The TM attachment footprint at the crest of the lesser tubercle had an average dimension of 187 ± 89 mm² . It was 49.6 ± 7.9 mm long and 7.4 ± 2.5 mm wide. The bony attachment of the LD within the bicipital groove, just below the tendon of the long head of the biceps muscle, had an area of 94 ± 37 mm² . It was 36.5 ± 8 mm long and 3.7 ± 1.2 mm wide. Both muscles were separated by 4.4 ± 1.7 mm and their attachments overlapped in the craniocaudal direction by 24.4 ± 12.4 mm. Earlier studies have investigated the dimensions of the muscles' tendons close to the attachment not the bony attachment itself. The dimension of the attachment of the TM was larger than that of the LD. The ratio between the footprint areas was approximately 2:1. This information should be considered by surgeons undertaking transfers, which include a bony segment of the muscle insertion.