The arcuate line is the inferior margin of the posterior leaflet of the rectus sheath within the abdomen. The posterior leaflet of the sheath is formed, superficial to deep, from the:
- posterior part of the internal oblique aponeurosis
- transversus abdominis aponeurosis
- transversalis fascia
Below the arcuate line, there is a transition so that all but the transversalis fascia pass anterior to rectus abdominis.
The arcuate line can be seen from the peritoneal surface of the rectus sheath as a superiorly convex line. It is roughly positioned half way between the umbilicus and the pubic crest.
Clinically, the arcuate line is important as the:
- site of entry of the inferior epigastric artery into the rectus sheath
- site of weakness: site of Spigelian hernia