Sternalis Muscle: An Uncommon Finding During Aesthetic Breast Surgery

The sternalis muscle is an uncommon anatomic variant of the chest wall musculature. It was first reported in Anatomes Elenchus Accuratissimus in 1604.1,2 Few reports of this muscle have appeared in the literature, and there is debate about its anatomic origin, insertions, function, and innervations. Reported as an inconstant finding in Netter’s Atlas ,3 the sternalis muscle is described as an analogous muscle that develops along with the rectus abdominis muscle but resorbs when chest development occurs during intrauterine life. Over the years, anatomists have coined a number of terms to refer to the sternalis muscle, such as the accessorius ad rectum and the parasternal, pectoris rectus , or praesternalis muscle .4 The sternalis is an accessory muscle that can originate from the upper sternum and the infraclavicular region, which inserts upon the anterior pectoral fascia, the lower ribs, the costal cartilages, the sheath of the rectus abdominis muscle, and the aponeurosis of the abdominal external oblique muscle. An adipose tissue layer can be interposed between the pectoralis major and sternalis muscles. Some anatomists consider the sternalis a rudiment of the panniculus carnosus in humans.5 Existence of the sternalis muscle varies between the sexes and among ethnic groups; it is reported in …