Relation of Transversus Abdominis to Rectus Abdominis Muscle in Various Anatomical Landmark Levels: A Cadaveric Study.

Background  Posterior Component Separation (PCS) is a surgical technique used in abdominal wall reconstruction. Understanding the relationship between the rectus abdominis and transversus abdominis muscles and the location of intercostal nerves is crucial for minimizing nerve injury during PCS. This cadaveric study aimed to investigate these anatomical relationships and propose practical guidelines for safer PCS procedures. Methods  Eighteen fresh cadavers were dissected to assess the overlap or separation of the rectus abdominis and transversus abdominis muscles at seven abdominal levels. The distance of intercostal nerves from the lateral border of the rectus abdominis was measured. Results  The study found that the muscles overlapped at the xiphoid and upper abdominal levels but began to separate below the 2/4 upper to umbilicus level. Intercostal nerves entered at varying distances from the lateral edge of the rectus abdominis, suggesting that levels above the 3/4 upper to umbilicus level are relatively safe for dissection. Conclusion  The study recommends initiating the first incision for PCS between the subxiphoid and 2/4 upper to the umbilicus, based on observed muscle relationships and nerve distances. This practical approach enhances safety and simplifies decision-making during surgery.