Arcuate line of rectus sheath

The arcuate line is visible upon the inner surface of the abdominal wall. The arcuate line may be a well-defined, or may be represented by a gradual waning of the aponeurotic fibres with concomitant increasing prominence of the transversalis fascia. The arcuate line occurs about midway between the umbilicus and pubic symphysis, however, this varies from person to person.

The inferior epigastric artery and vein pass across the arcuate line to enter the rectus sheath.

Anatomy

Superior to the arcuate line, the internal oblique muscle aponeurosis splits to envelop the rectus abdominis muscle both anteriorly and posteriorly. The anterior layer is derived from the external oblique aponeurosis and the anterior lamina of the internal oblique aponeurosis. The posterior layer is made up of the posterior lamina of the internal oblique aponeurosis and the transversus abdominis aponeurosis.

Inferior to the arcuate line, the aponeuroses of the external oblique muscle, the internal oblique muscle, and the transversus abdominis muscle merge and pass superficial to the rectus abdominis muscle. Therefore, inferior to the arcuate line, the rectus abdominis rests directly on the transversalis fascia.