Seven-Headed Sternalis: A Case Report with Three-Dimensional Presentation Using Photogrammetry

The sternalis muscle, a well-documented anatomical variation in the chest muscles, has garnered attention in anatomical research but remains relatively unfamiliar to clinicians and radiologists. This variation exhibits a wide array of descriptions and classifications in the literature, emphasizing its highly variable characteristics. This study presents a new variant of the sternalis muscle with seven muscle bellies in a 79-year-old male donor. Bilateral accessory heads of the sternocleidomastoid muscles gave rise to two superior heads. Furthermore, five additional heads originated from the pectoralis major fascia, with three on the left and two on the right, together having widths of 6.6 cm on the left and 5.3 cm on the right. Innervation of the inferior heads was provided by the intercostal nerves. The configuration of the sternalis muscle with seven heads found in this study is exceptionally distinctive and has never been reported. This unique anatomical variation, coupled with three-dimensional imaging using photogrammetry, offers valuable insights for clinicians, especially in the context of breast surgery.