The rectus abdominis runs vertically between the pubis and the costal cartilages, interrupted by three horizontal tendinous intersections at the umbilicus, xiphoid, and midway between. It is enclosed in the rectus sheath formed by the aponeuroses of the obliques and transversus abdominis. Below the arcuate line (midway between umbilicus and pubis) the posterior sheath is absent — only the transversalis fascia covers the posterior rectus.
| Origin | Pubic symphysis and pubic crest |
|---|---|
| Insertion | Costal cartilages of ribs 5-7 and xiphoid process |
| Nerve Supply | Intercostal nerves T5-T12 (segmental supply — each rectus segment has its own nerve) |
| Blood Supply | Superior and inferior epigastric arteries within the rectus sheath |
| Actions | Trunk flexion (primary spinal flexor); Compresses abdominal viscera; Tilts the pelvis posteriorly; Assists forced expiration |
|---|
The DIEP flap for breast reconstruction is based on perforators from the deep inferior epigastric artery that pierce the rectus abdominis to reach the skin. Rectus abdominis diastasis (separation at the linea alba) from pregnancy or obesity is corrected by plication of the medial rectus edges. The rectus sheath haematoma from inferior epigastric artery injury produces a painful abdominal mass.
The rectus abdominis is palpable in the midline abdomen between the pubis and xiphoid, becoming visible as the 'six pack' when hypertrophied and lean.
Trunk flexion overload producing acute midline abdominal pain managed with rest and progressive loading rehabilitation.
