Clinical and Molecular Insights into Biology Diagrams The lower esophageal sphincter is a valve between your esophagus and stomach. It prevents stomach contents from going back up the esophagus. The lower esophageal sphincter (LES), also termed the cardiac sphincter and cardioesophageal sphincter, is located slightly more than an inch (about 3 cm) proximally from where the esophagus meets the stomach. Similar to the UES, the LES is normally contracted and closed, primarily preventing stomach contents from entering the esophagus body. The upper esophageal sphincter (UES) is a high-pressure zone at the transition of the pharynx and the cervical esophagus. The lower esophageal sphincter (LES) is a high-pressure zone located where the esophagus meets the stomach and protects the esophagus from the reflux of gastric contents.
Abstract: The upper esophageal sphincter (UES), also known as the pharyngoesophageal segment (PES), is a 4-cm segment of the digestive tract that separates the esophagus from the pharynx and larynx. This narrative review represents an overview of the anatomy and physiology of this critical component of the airway protective mechanism. Upper esophageal sphincter is composed of all skeletal muscles and lower esophageal sphincter of all smooth muscles. Based on the studies in mice embryo, esophagus is comprised of entirely smooth muscles at the beginning that slowly transdifferentiate into the skeletal muscles during later embryological age until few days after birth [54].
The Oesophagus Biology Diagrams
There are two sphincters present in the oesophagus, known as the upper and lower oesophageal sphincters. They act to prevent the entry of air and the reflux of gastric contents respectively. Upper Oesophageal Sphincter The upper sphincter is an anatomical, striated muscle sphincter at the junction between the pharynx and oesophagus. How does the esophagus work? At the opening of your upper esophagus, there's a ring-shaped muscle called the upper esophageal sphincter. Your upper esophageal sphincter senses when food or liquid is coming toward it. When it gets the signal, the sphincter relaxes or opens so that food can enter your esophagus. Esophagus: Anatomy & Physiology Anatomy Layers Mucosa (Squamous Epithelium) Submucosa Muscularis Propria (Longitudinal) Upper 1/3: Striated Lower 2/3: Smooth No Serosa Importance: CA Spreads Through Lymphatics Sphincters Upper Esophageal Sphincter (UES) Cricopharyngeus Muscle 15 cm From Incisors Most Common Site of Iatrogenic Perforation and Foreign Body Prevents Air Swallowing Innervation
