Two Cases of Rectus Sternalis Muscle

Area of Science:

• Anatomy
• Medical Imaging
• Surgical Reconstruction

Background:

• The sternalis muscle is an uncommon chest wall variant, often overlooked by clinicians and radiologists.
• Despite its rarity, recent efforts emphasize its clinical relevance.

Observation:

• Two distinct sternalis muscle cases were observed during routine anatomical dissection.
• Case 1: Unilateral right sternalis with contralateral insertion on the left sternocleidomastoid.
• Case 2: Bilateral sternalis muscle with ipsilateral insertion.

Findings:

• The unilateral sternalis muscle was innervated by the medial pectoral nerve.
• The bilateral sternalis muscle received innervation from lower intercostal nerves.
• The sternalis muscle exhibits wide-ranging prevalence and morphology, with differing opinions on its development and nerve supply.

Implications:

• Sternalis muscle presence can mimic chest wall lesions, leading to misdiagnosis.
• This muscle variant is valuable for reconstructive surgery, including pedicle flaps and microvascular anastomosis in the chest, head, neck, and breast regions.