[Anatomical study of the twelfth intercostal nerve and oblique lumbotomies (author's transl)].

After a very precise anatomical review, the authors report the results of an anatomo-radiological study involving 244 urography films. The usual length of the 12th rib is 11 cm, with a width of 1 cm in the female and 1.5 cm in the male. The costo-lumbar angle was 45 degrees in 3/4 of the films. The kidney was often lower in the female than in the male. The renal artery was almost always given off at the level of the 12th rib or below, whilst at the level of the hilum, the renal artery and 12th rib having crossed, the artery was always above the 12th rib. Study of 173 usable cases of patients operated upon by lumbotomy revealed the following data: --lumbotomies on the 12th rib never opened the pleura, and gave rise to transient wall pain (7%) and one single case of abdominal wall hypotonia (1.4%) with no incisional hernias; --lumbotomies over the 11th rib were associated with 13% of cases of damage to the pleura, 16% of spontaneously resolving wall pain, 7 cases of prolonged parietal hypotonia and one incisional hernia out of 60 lumbotomies; --lumbotomies sub-jacent to the 12th rib were associated with residual abdominal wall pain in 3 cases out of 16. Lumbotomies over the 11th rib are associated with the risk of section of the superficial and deep abdominal branch of the 12th nerve and are hence those exposing to the greatest risk of abdominal wall hypotonia and neuralgia. Incision over the 12th rib would thus appear to be that associated with the least abdominal wall complications.