Muscular Architecture and Manometric Image of Gastroesophageal Barrier in the Rat

The two components of the gastroesophagealbarrier, the sphincter and the crural sling, closelyoverlap in humans, whereas they are widely separated inthe rat. This investigation correlates the anatomical components of the barrier and their manometriccounterparts in this animal. Sphincteric and cruralsling pressures were measured in four quadrants in 23rats. Muscle thickness was measured at nine levels of the gastroesophageal junction in the samequadrants in 12 rats and the muscular architecture ofthe region was studied in 10 fresh specimens. Themanometric sphincteric component is stronger on theright side where the thickest muscle fibers anchor tothe anterior and posterior borders of a mucosal ridgethat almost surround the cardia. Conversely, the slingpressure is highest towards the left where the muscular bundles straddle the esophagus. Inconclusion, there is a close correspondence between themanometric image and the muscular architecture of thecomponents of the gastroesophageal barrier in the rat. The anatomical arrangement of U-shapedmuscular bundles oriented in opposite directions createsa particularly powerful antireflux mechanism.