Study of abdominal wall muscle innervation applied to large-defect closure in congenital diaphragmatic hernia

In large congenital diaphragmatic hernias (CDHs), direct suture of the diaphragm is impossible. Surgeons can use a triangular internal oblique muscle (IOM) plus transverse abdominis muscle (TAM) flap. Its caudal limit faces the medial extremity of the 11th rib. Clinical studies show that the flap is not hypotonic but that the procedure could expose patients already presenting a hypoplastic lung to external oblique muscle (EOM) hypotonia. The aims of this study were to study EOM innervation by the 10th intercostal nerve (ICN) and ICN innervation to the IOM and TAM. Forty cadaveric abdominal hemi-walls were dissected. The number of branches and the trajectory of each specimen's 10th ICN were studied medially to the medial extremity of the 11th rib (MEK11) using surgical goggles and a microscope (Carl Zeiss®). The 10th ICN was consistently found between the IOM and TAM. There was a median of nine branches from the 10th ICN to the EOM, 77% of them medial to the MEK11. Median values of nine and 12 branches for the IOM and TAM were found, 60% and 51%, respectively, medial to the MEK11. These results argue in favor of good innervation to the IOM plus TAM flap but also indicate postoperative abdominal weakness exposing patients to herniation risks, as more than 75% of the branches from the 10th ICN to the EOM were sectioned or pulled away during flap detachment. Clin. Anat., 33:759-766, 2020. © 2019 Wiley Periodicals, Inc.