A neuromuscular basis for development of indirect inguinal hernia.

Specialized portions of the transversus abdominus muscles act on the internal inguinal rings and produce a closure mechanism during voluntary abdominal muscular activity. Abdominal muscular contractions may have a protective influence against development of indirect inguinal hernia. It follows, therefore, that injury or inactivation of this mechanism may be an etiologic factor in the development of indirect inguinal hernia. One cause of injury to this mechanism is by denervation and regional muscle paralysis occurring during a surgical procedure. Surgical denervation appears to have caused an indirect inguinal hernia in one of the authors.