The longitudinal fibromuscular band of the anal canal

Abstract Objective There are many studies in the literature about the physiological and incontinence mechanisms of the anal region. However, there is a lack of information about the detailed anatomy and function of the longitudinal fibromuscular band. We have therefore studied the longitudinal fibromuscular band and its effect on the anal canal and the continence mechanism. Materials and methods The anal canals of 12 pelves of fixed cadavers abdominoperineal excision specimens were studied using a surgical microscope. Results The longitudinal fibromuscular band terminates in three fibers extending downward. Medial fibers of the band reach the most inferior part of the circular fibers of the internal anal sphincter and end at the anocutaneous line. Lateral fibers run below the superficial parts of the external anal sphincter and terminate at the ischioanal fossa. Inferior fibers spread radially in and below the subcutaneous part of the external anal sphincter and terminate in the subcutaneous. Conclusion The longitudinal fibromuscular band may play a role in incontinence because it supports the sphincter muscles in the anal canal from below. When the internal anal sphincter muscles relax, the longitudinal fibromuscular band located lateral to these muscles can assist with defecation. This will facilitate a better understanding of the mechanisms of incontinence. The anatomy of the anal canal is important in reducing the risk of recurrence in the surgical treatment of lower rectal tumors.