Sternalis muscle: an underestimated anterior chest wall anatomical variant

Athanasios Raikos,Panagiota Kordali,Maria Tzika,Pedro Faustmann,Beate Brand-Saberi,Panagiotis Kitsoulis,Stefanos Triaridis,George K Paraskevas

doi:10.1186/1749-8090-6-73

Abstract

Over the recent years, an increased alertness for thorough knowledge of anatomical variants with clinical significance has been recorded in order to minimize the risks of surgical complications. We report a rare case of bilateral strap-like sternalis muscle of the anterior chest wall in a female cadaver. Its presence may evoke alterations in the electrocardiogram or confuse a routine mammography. The incidental finding of a sternalis muscle in mammography, CT, and MRI studies must be documented in a patient's medical records as it can be used as a pedicle flap or flap microvascular anastomosis during reconstructive surgery of the anterior chest wall, head and neck, and breast. Moreover, its presence may be misdiagnosed as a wide range of benign and malignant anterior chest wall lesions and tumors.

Highlights

The sternalis muscle is an anatomical variant of the anterior thoracic region musculature well documented and familiar to anatomists but quite unknown among clinicians and radiologists [1]
The muscle usually arises from the upper sternum and the infraclavicular region and can display variable insertion points such as the pectoral fascia, lower ribs, costal cartilages, rectus abdominis muscle sheath or the abdominal external oblique muscle aponeurosis [4,5]
We describe a rare observation of a bilateral sternalis muscle in a female cadaver, and we discuss about the muscle’s possible embryological origin, innervation, and clinical significance

Summary

Introduction

The sternalis muscle is an anatomical variant of the anterior thoracic region musculature well documented and familiar to anatomists but quite unknown among clinicians and radiologists [1]. It lies superficially and perpendicular to the pectoralis major muscle and parallel to the sternum. The muscle usually arises from the upper sternum and the infraclavicular region and can display variable insertion points such as the pectoral fascia, lower ribs, costal cartilages, rectus abdominis muscle sheath or the abdominal external oblique muscle aponeurosis [4,5]. Its presence ranges from a few short fibers to a well-formed muscle, found unilaterally or bilaterally. Variation exists in the reported incidence among different populations ranging from 1% in Taiwanese to 18.2% in North Chinese [7,8]. According to Scott-Corner et al, it is more usual in females (8.7%) than in males (6.4%) [9]

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Discussion

Conclusion