Pyloric sphincter

The pyloric sphincter is a specialized ring of smooth muscle located at the distal end of the stomach, serving as the gateway to the duodenum. Its primary biological function is to regulate the passage of chyme from the stomach into the small intestine, ensuring optimal digestion and absorption while preventing the reflux of duodenal contents back into the stomach (StatPearls, 2023). The sphincter remains in a tonic state of contraction and relaxes in response to neural and hormonal signals to allow controlled gastric emptying. Dysfunction of this sphincter is central to several clinical conditions, most notably hypertrophic pyloric stenosis in infants and gastroparesis in adults (NIH, 2022). While not a single molecular target itself, the pyloric sphincter is modulated by various pharmacological agents that act on its constituent receptors, such as muscarinic, adrenergic, and motilin receptors. For instance, botulinum toxin injections are sometimes used to relax the sphincter in cases of refractory gastroparesis, and prokinetic agents like erythromycin can influence its motility (PubMed, 2021). Understanding its physiological control is crucial for managing disorders of gastric motility and outlet obstruction.

Other names

PylorusPyloric valveSphincter pylori

Modulation of smooth muscle tone via autonomic and enteric nervous system signaling (e.g., cholinergic, nitrergic) and hormonal pathways (e.g., motilin, cholecystokinin) (StatPearls, 2023).