On the clinical significance of the sternalis muscle.

During routine anatomical dissection, two cases of sternalis muscle were described. In the first case a unilateral sternalis on the left side was observed. It started from the fibres of the sternal membrane, then passed downwards in a slightly arch-shaped course and ended in the pectoral fascia at the level of 6-7 costal cartilages. In the second case, a bilateral sternalis muscle composed of two bellies (right and left) was detected. It arose from the sternal membrane covering the sternal angle. The right belly was attached to the fourth costal cartilage at the sternal junction; the left one was inserted into the third costal cartilage also at the sternal junction. In these cases sternalis muscles were supplied by perforating branches of the internal thoracic arteries and innervated by anterior branches of the intercostal nerves. We have also reviewed the available literature concerning the clinical importance of the sternalis and summarized it clearly for clinical anatomists, plastic surgeons, breast surgeons and radiologists.