From the Guidelines
The gastroesophageal junction sphincter is primarily maintained by the lower esophageal sphincter (LES), which is supported by the crural diaphragm, and influenced by factors such as the angle of His, intra-abdominal pressure, hormonal changes, and neural regulation. When considering the factors that contribute to the gastroesophageal (GE) junction sphincter, it is essential to understand the complex interplay of anatomical and physiological components. The LES, a specialized ring of muscle, provides the primary barrier function against reflux, and its pressure is influenced by various factors, including gastrin, which increases LES pressure, while progesterone and estrogen can decrease it 1. The crural diaphragm, which wraps around the LES, provides additional pressure during breathing, further supporting the sphincter's function. Other factors, such as the angle of His, formed where the esophagus meets the stomach, create a valve-like effect that helps prevent reflux. Additionally, the intra-abdominal portion of the esophagus experiences positive pressure from the abdomen, which compresses this segment and enhances the barrier. Lifestyle measures, such as weight loss, avoiding late evening meals, and elevating the head of the bed, can also help reduce reflux symptoms by decreasing pressure on the LES and improving nocturnal esophageal acid exposure 1. Key factors contributing to the GE junction sphincter include:
- Lower esophageal sphincter (LES)
- Crural diaphragm
- Angle of His
- Intra-abdominal pressure
- Hormonal influences (gastrin, progesterone, estrogen)
- Neural regulation (vagus nerve, enteric nervous system)
- Phrenoesophageal ligament These components work together to create an effective barrier that prevents stomach contents from flowing backward into the esophagus while still allowing food and liquids to pass into the stomach during swallowing.
From the Research
Gastroesophageal Junction Sphincter Contributions
The gastroesophageal (GE) junction sphincter is contributed to by several factors, including:
- Lower esophageal sphincter (LES) function, which is the primary cause of gastroesophageal reflux disease (GERD) 2, 3, 4
- Anatomic configuration of the esophagogastric junction (EGJ) complex, which plays a role in preventing backflow of gastric contents into the esophagus 5
- Backflow-preventive pressure on the LES, which helps to maintain the integrity of the sphincter 5
- Backflow-promotive pressure across the LES, which can contribute to the development of GERD 5
- Gastric distension, which can affect the function of the LES by increasing wall tension and contributing to sphincter opening 6
- Mucosal seal, which helps to prevent the reflux of gastric contents into the esophagus 6
- Length of the sphincter, which can contribute to sphincter competence by decreasing the importance of gastric wall tension in sphincter opening and improving the mucosal seal 6
Key Factors
Some key factors that contribute to the GE junction sphincter include:
- LES pressure integral, which is a measure of the pressure exerted by the LES to prevent backflow of gastric contents 5
- Thoracoabdominal pressure gradient, which can contribute to the development of GERD by increasing the pressure across the LES 5
- EGJ morphology, which can affect the function of the LES and contribute to the development of GERD 5