A Unilateral Rectus Sternalis Muscle: Rare But Normal Anatomical Variant of Anterior Chest Wall Musculature

Introduction: Rectus Sternalis muscle, an uncommon anatomical variant of the chest wall musculature, is regularly present in lower animals and is occasionally detected in humans. Lack of acquaintance of the clinicians with this muscle variant may cause negative changes in prognosis of patient. The anatomical and embryological details of Rectus Sternalis muscle in this article may help clinicians in interventional procedures, in prevention of diagnostic errors and in avoiding complications during any surgery which is done in the pectoral region. Material and Methods: This was a cadaveric study which was conducted as a pilot study, to know the baseline information about the incidence of Rectus Sternalis muscle among cadavers in Indian region. During a period of three years, 30 properly embalmed cadavers of Indian origin were dissected in dissection hall of Anatomy Department, S.M.S. Medical College (Jaipur, Rajasthan) during routine dissections, which is a part of medical education. Dissections of pectoral regions of these 30 cadavers were performed, to know the presence of Rectus Sternalis muscle. Observation and result: Rectus Sternalis muscle was found only in one cadaver, as a vertical strip of muscle in the anterior chest wall musculature. It was present unilaterally at right-side in anterior chest wall, superficial to pectoralis major muscle. Present study provides the initial estimates towards baseline information about the incidence of Rectus Sternalis, which was 3.3% among the cadavers of Indian origin in this study. Conclusion: Rectus Sternalis is a rare but a normal anatomical variant in the anterior chest wall musculature and knowledge on it is important, for interventional and diagnostic procedures which are related to this region.