Medical anatomy diagram of the rectus sheath showing cross-sectional view above and below the arcuate line. Two labeled diagrams side by side: LEFT labeled "Above Arcuate Line" showing anterior wall = external oblique aponeurosis + anterior half of internal oblique aponeurosis, rectus abdominis muscle in center, posterior wall = posterior half of internal oblique + transversus abdominis aponeurosis, transversalis fascia, peritoneum. RIGHT labeled "Below Arcuate Line" showing all three aponeuroses forming only anterior wall, no posterior sheath, only transversalis fascia posteriorly. Clean medical textbook style with color-coded layers and clear labels.

Medical anatomy diagram showing contents of the rectus sheath: rectus abdominis muscle, pyramidalis muscle, superior epigastric artery and vein, inferior epigastric artery and vein with their anastomosis, thoracoabdominal nerves T7-T12 entering laterally. The diagram shows a frontal/anterior view of the abdominal wall with the anterior layer of the rectus sheath cut open to reveal these structures. Clean anatomical illustration style with labeled arrows, medical textbook quality.