The sternalis muscle in cadavers: anatomical facts and clinical significance.
ABSTRACT The sternalis is an anomalous muscle located in the anterior wall of thorax and several past reports have described its presence with clinical implications. The sternalis muscle may be incidentally detected during routine cadaveric dissections and autopsies. We observed the presence of anomalous sternalis muscle on both sides of the anterior chest wall in 25 cadavers (n = 50), over a span of three years. Out of a 50 cases, we observed a single case of sternalis on the right side of the 55-year-old male cadaver (2%). The sternalis was found to be absent in the rest 49 cases (98%). The sternalis muscle displayed an oblique course in the anterior wall of the thorax. The muscle originated near the seventh costal cartilage extending obliquely upwards to insert into the second costal cartilage close to the sternum. The originating portion of the muscle was located at a distance of 3.5 cm lateral to the mid-sternal plane. The vertical length and the maximum width of the anomalous sternalis muscle measured 9 cm and 1.9 cm, respectively. The fibers of the muscle vertically ascended upwards. No other associated anomalies were observed in the same cadaver. The presence of sternalis muscle is considered to be a rare variation with no earlier studies being performed in the Malaysian population. The anomalous sternalis muscle may be important for reconstructive surgeons performing mastectomy and radiologists interpreting mammograms. Thus, the sternalis muscle may be academically, anthropologically and surgically important.
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ABSTRACT: The sternalis muscle is an anatomic variation well known to anatomists, but relatively unknown to clinicians and surgeons. It is localized superficially to the pectoralis major and can cause a diagnostic dilemma during breast surgery, mammography, and computed tomography and magnetic resonance imaging scans, as its appearance mimics tumor pathology of the region. We studied the presence of longitudinally placed muscles in the anterior thoracic wall in 45 cadavers (90 hemithoraces). In an 83-year-old white male, a rare case of crossed-type sternalis was detected on the left side. The muscle originated from the sternal head of the right sternocleidomastoid, crossed into the opposite parasternal half, and split into 2 tendons and 2 muscle bellies that inserted into the left subcostal arch region. This variant was not included in the available sternalis classifications, and an update is suggested. The muscle is of utmost importance and diagnostic value in routine mammogram screening. Moreover, it is of great value for the plastic surgeon, because identification of the variant can aid the differential diagnosis among other regional lesions. Likewise, its superficial location makes it an ideal candidate for utilization as a muscular flap in plastic reconstruction of the head and neck region.Annals of plastic surgery 03/2011; 67(6):646-8. · 1.29 Impact Factor