Function of longitudinal vs circular muscle fibers in esophageal peristalsis, deduced with mathematical modeling

• Published in: World journal of gastroenterology : WJG Vol. 13; no. 9; pp. 1335 - 1346
• Main Authors: Brasseur, James G, Nicosia, Mark A, Pal, Anupam, Miller, Larry S
• Format: Journal Article
• Language: English
• Published: United States Department of Mechanical Engineering,Pennsylvania State University,University Park,PA 16802,United States%Department of Mechanical Engineering,Widener University, Chester, PA 19013, United States%Department of Biological Sciences & Bioengineering,Indian Institute of Technology Kanpur,UP, 208016,India%Department of Gastroenterology, Temple University Medical Center, Philadelphia, PA 19140, United States 07.03.2007; Baishideng Publishing Group Co., Limited
• Subjects: Biomechanical Phenomena; Esophageal Motility Disorders - physiopathology; Esophagus - diagnostic imaging; Esophagus - physiology; Gastroesophageal Reflux - physiopathology; Humans; Models, Biological; Models, Theoretical; Muscle Contraction - physiology; Muscle, Smooth - diagnostic imaging; Muscle, Smooth - physiology; Peristalsis - physiology; Topic Highlight; Ultrasonography; 数学模型; 肌纤维; 食管蠕动; Longitudinal shortening; Circular muscle; Peristalsis; Longitudinal muscle; Esophagus
• ISSN: 1007-9327; 2219-2840
• DOI: 10.3748/wjg.v13.i9.1335

We summarize from previous works the functions of circular vs. longitudinal muscle in esophageal peristaltic bolus transport using a mix of experimental data, the conservation laws of mechanics and mathematical modeling. Whereas circular muscle tone generates radial closure pressure to create a local peristaltic closure wave, longitudinal muscle tone has two functions, one physiological with mechanical implications, and one purely mechanical. Each of these functions independently reduces the tension of individual circular muscle fibers to maintain closure as a consequence of shortening of longitudinal muscle locally coordinated with increasing circular muscle tone. The physiological function is deduced by combining basic laws of mechanics with concurrent measurements of intraluminal pressure from manometry, and changes in cross sectional muscle area from endoluminal ultrasound from which local longitudinal shortening （LLS） can be accurately obtained. The purely mechanical function of LLS was discovered from mathematical modeling of peristaltic esophageal transport with the axial wall motion generated by LLS. Physiologically, LLS concentrates circular muscle fibers where closure pressure is highest. However, the mechanical function of LLS is to reduce the level of pressure required to maintain closure. The combined physiological and mechanical consequences of LLS are to reduce circular muscle fiber tension and power by as much as 1/10 what would be required for peristalsis without the longitudinal muscle layer, a tremendous benefit that may explain the existence of longitudinal muscle fiber in the gut. We also review what is understood of the role of longitudinal muscle in esophageal emptying, reflux and pathology.