The clinical anatomy of the triangle of Grynfeltt

Dorsal lumbar hernias are rare pathologies of the abdominal wall. Such hernias may manifest within the superior lumbar triangle of Grynfeltt (TG) or the triangle of Petit. The aim of our study was to identify and describe variations in the size and anatomy of the TG. The triangle was studied in 50 adult human cadavers, and dimensions and surface area were measured. The TG was identified in 82% of cases. Based on surface area parameters, we were able to classify the triangles into four distinct types. Type I (50%), or small triangles, had a surface area of <5 cm². Type II (22%, n = 22) were defined as triangles intermediate in size with surface areas of 5-15 cm². Type III (10%, 10) were large triangles with surface areas of >15 cm². Finally, Type 0 (18%, 18) did not exhibit a triangle; instead, the aponeurosis of the transversus abdominis was enclosed by the external abdominal oblique muscle and the sacrospinalis muscle. We present these data with the hope that after further investigation in a clinical setting, they may serve practitioners in predicting which morphometric variations of the TG most predispose patients to posterior wall herniation.