 The sternalis muscle often originates from the upper part of the sternum and can display varying insertions such as the pectoral fascia, lower ribs, costal cartilages, rectus sheath, aponeurosis of the abdominal external oblique muscle.There is still a great deal of disagreement about its innervation and its embryonic origin.In a review, it was reported that the muscle was innervated by the external or internal thoracic nerves in 55% of the cases, by the intercostal nerves in 43% of the cases, while the remaining cases were supplied by both nerves.