The puborectalis muscle.

The role of the levator ani and puborectalis muscle in preserving continence has been underestimated in the past, due predominantly to technical difficulties to investigate its proper function in healthy subjects, and its dysfunction as in patients with incontinence problems. This has recently been overcome by applying new investigational procedures such as a perineal dynamometer which measures the traction exerted by the levator ani on an intrarectal balloon catheter, or by multi-electrode arrays recording the generation of motor unit action potentials from various parts of the puborectalis muscle sling via intrarectal surface electrodes. Both techniques have the potential to provide new insights into the physiology of defecation and the pathophysiology of incontinence and constipation.