Rectus abdominis muscle innervation: an anatomical study with surgical implications in diep flap harvesting.

PURPOSE: To improve the current knowledge of rectus abdominis innervation, so as to identify a safe area where the vascular pedicle should be dissected to reduce the risk of nerve damage during deep inferior epigastric perforator (DIEP) flap harvesting.

METHODS: Ten abdominal wall dissections were performed. Perforating arteries were identified and classified into nerve-related perforators and non-nerve-related perforators depending on the presence of nerve branches crossing vessels. The width of rectus abdominis and the distance between perforators and lateral edge of rectus abdominis muscle were measured. In contralateral hemi-abdomen, full-thickness specimens were sampled for microscopical analysis.

RESULTS: Nerves enter the rectus sheath piercing the lateral edge (60% of cases) or the posterolateral surface of the sheath (40% of cases). They enter the rectus abdominis muscle at a mean distance of 4.3 cm from the lateral margin of the sheath. Within rectus abdominis, nerves have a mean thickness of 200.3 µm and split into 2-4 sensitive and 2-4 muscular branches. Close relationship between muscular branches and deep inferior epigastric artery perforators were shown. The mean distance between nerve-related perforators and the lateral edge of the rectus abdominis was of 3.26 ± 0.88 cm. The mean distance between non-nerve-related perforators and the lateral edge of the rectus abdominis was of 6.26 ± 0.90 cm.

CONCLUSIONS: To spare nerves and reduce donor-site complications, a perforator located beyond an imaginary line of 3.26 ± 0.88 cm far from the lateral edge of rectus abdominis muscle should be included in the DIEP flap.