Arcuate line of the rectus sheath: an anatomist’s viewpoint

Abstract

The article titled ‘Arcuate line of the rectus sheath: clinical approach’ by Loukas et al. generates much interest (Loukas et al. 2008). The authors should be applauded for their meticulous work. It was very surprising to find the omission of the ‘arcuate line’ as a possible keyword. Medline had previously accepted it as a possible keyword, so an important keyword might have been missed. The topographical anatomy of the arcuate line has been reported in the past, and the authors took special interest in citing all those works. The presence of AL on both sides of 100 cadavers is an interesting finding. Past studies have reported a prevalence rate of 14.97 and 1.35% in males and females, respectively (Coulier 2007). The authors describe that the existence of AL has been a subject of debate. Interestingly, the slower rate of the fibers of the rectus sheath from the posterior to anterior direction may result in the absence of AL, which occurs in 70% of cases (Rizk 1991). Likewise, the rapid rate of shifting of fibers from the posterior to anterior rectus sheath may account for the existence of double AL (Rizk 1991). The authors should have mentioned if the medial or the lateral end of the AL was higher. This is one of the most fundamental observations when describing the topographical anatomy of AL. Yes, I do agree with the authors that the exact topographical anatomical location of the AL may vary. Does the topographical anatomy of the AL really matter to a surgeon before opening up the abdomen? It has to be remembered that any physical activity such as sports may change the morphometric indices and echogeneity of the abdominal wall muscle (Kogut et al. 1993). Simply by observing that an individual is obese, one cannot have the preconception that the AL will vary considering that knowing the history of any physical activity of the individual is equally important. The authors should have mentioned clearly what they meant by evidence of any previous surgical procedures. Incisional marks predispose to hernias, but those marks may not always be visible. A proper clinical history of the individual is necessary. Spigelian hernia was mentioned as a keyword, but no anatomical details were specifically mentioned about this hernia. This kind of hernia usually affects the younger age group, and the association of this hernia with other congenital defects assumes much clinical importance. Below the umbilicus, the fibers of the internal oblique and the transverse abdominis muscles run parallel to each other, thereby accounting for the increase in incidence of Spigelian hernias, but above the umbilicus, the fibers of the internal oblique and transverses abdominis cross each other at right angles, thereby accounting for the reduced chance of occurrence of Spigelian hernias (Rehman et al. 2000). The article has highlighted all the necessary details pertaining to AL. I thank the authors and the editor for publishing such an important article.