Microanatomy of the structures contributing to abdominal cutaneous nerve entrapment syndrome

Family physicians commonly see patients who complain of abdominal pain, the cause of which cannot be readily diagnosed. Often this pain results from abdominal cutaneous nerve entrapment syndrome.

Photomicrographs were obtained of the pertinent structures of the ninth thoracolumbar nerve where it passes through the rectus muscle channel. Standard hematoxylin and eosin staining techniques were used after the paraffin autopsy tissue block was positioned to show the entire length of the rectus neurovascular bundle from anterior to posterior surfaces of the muscle (anatomically front to back). Gomori trichrome staining with aniline blue was also done to differentiate further the connective tissue structures.

The photomicrographs presented here support the first author's earlier clinical and gross anatomic findings, especially regarding the fibrous ring in the rectus muscle, through which the neurovascular bundle travels. Special attention is given to the rectus fibrous ring, which is so important in producing the syndrome of abdominal cutaneous nerve entrapment. This structure is clearly delineated, and its role in the pathophysiology of this syndrome is described.

Three pictures presented here show the relevant microstructures involved in abdominal cutaneous nerve entrapment syndrome. The photomicrographs confirm the existence of a fibrous ring within which the neurovascular bundle can move freely. If this bundle is pushed or pulled too far from behind or in front, however, compression of the bundle against the ring causes nerve ischemia and symptoms of abdominal cutaneous nerve entrapment. Family physicians can save their patients unnecessary pain and expense by being aware of this syndrome.