Logan Steele
The oesophagus is a muscular tube that carries food and liquid from the throat to the stomach. It is surrounded at the top and bottom by two muscular rings, known as the upper and lower oesophageal sphincters (UES and LES). The UES is a 4-cm segment of the digestive tract that separates the oesophagus from the pharynx and larynx. It is formed by the lower portion of the inferior pharyngeal constrictor, also known as the cricopharyngeal sphincter. The UES controls the inflow and outflow through the region, preventing aerophagia in the anterograde direction and regurgitation in the retrograde. The LES is located where the oesophagus meets the stomach and protects the oesophagus from the reflux of gastric contents.
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What You'll Learn
- The upper esophageal sphincter (UES) is a high-pressure zone
- The UES is a 4-cm segment of the digestive tract
- The UES is not a true sphincter
- The primary muscle of the UES is the cricopharyngeal part of the inferior pharyngeal constrictor
- The UES is controlled by intrinsic muscular control and displacement
The upper esophageal sphincter (UES) is a high-pressure zone
The UES guards the entrance of the esophagus, controlling inflow and outflow through the region. It prevents aerophagia in the anterograde direction and regurgitation in the retrograde. The UES is a finely tuned mechanism that coordinates with the respiratory system to prevent penetration and aspiration into the larynx and trachea. The UES works in conjunction with the epiglottis, which tilts backward during swallowing to prevent food from entering the larynx and lungs.
The primary muscle of the UES is the cricopharyngeal part of the inferior pharyngeal constrictor. The UES is not a true sphincter, as it does not meet the definition of an annular muscle surrounding and able to contract or close a bodily opening. Instead, the UES is a complex structure that includes the cricopharyngeus muscle (CPM), which is often considered synonymous with the UES, but in reality, it is just one component of the UES anatomy. The UES is under intrinsic muscular control, and its opening is coordinated with the relaxation of the CPM, elevation of the larynx, and propulsion of the food bolus by the pharynx.
The UES is a critical component of the airway protective mechanism, and its function is essential for the proper coordination of the digestive and respiratory systems. The UES is a high-pressure zone, and its closure is maintained by the pressure of the larynx pressing it closed against the spine. This closure ensures that the UES remains shut when food is not being swallowed, protecting the esophagus and preventing regurgitation.
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The UES is a 4-cm segment of the digestive tract
The upper esophageal sphincter (UES) is a 4-centimetre segment of the digestive tract that separates the oesophagus from the pharynx and larynx. The UES is bounded anteriorly by the larynx, posterolaterally by the pharyngoesophageal muscles, superiorly by the pharynx, and inferiorly by the oesophagus.
The UES controls the inflow and outflow through the region, preventing aerophagia in the anterograde direction and regurgitation in the retrograde. The UES is not a true sphincter, as it does not meet the definition of an annular muscle surrounding and able to contract or close a bodily opening. Instead, the UES consists of cartilaginous, bony, and muscular components that open and close based on intrinsic muscular control and displacement.
The UES is formed by the lower portion of the inferior pharyngeal constrictor, also known as the cricopharyngeal sphincter, due to its relation to the cricoid cartilage of the larynx anteriorly. The UES is a high-pressure zone at the transition of the pharynx and the cervical oesophagus. The UES is guarded by the larynx, which presses the UES closed against the spine. The UES opens during swallowing, when the larynx is elevated off the spine by cervical and pharyngeal muscles, decreasing the pressure required by the pharynx to push food into the UES.
The oesophagus is a muscular tube that connects the pharynx to the stomach, providing peristaltic contractions in response to swallowing that propel food into the stomach. The oesophagus is surrounded at the top and bottom by two muscular rings, known as the UES and the lower oesophageal sphincter (LES). These sphincters act to close the oesophagus when food is not being swallowed. The LES is located where the oesophagus meets the stomach and protects the oesophagus from the reflux of gastric contents.
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The UES is not a true sphincter
The upper esophageal sphincter (UES) is a high-pressure zone at the transition of the pharynx and the cervical esophagus. It is formed by the lower portion of the inferior pharyngeal constrictor, also known as the cricopharyngeal sphincter due to its relation to the cricoid cartilage of the larynx.
The UES has two major functions: to prevent air from entering the esophagus during breathing and to prevent reflux of esophageal contents into the pharynx to guard against airway aspiration. The UES is innervated by the glossopharyngeal, branches of the vagus nerve, ansa cervicalis, and sympathetic nerves. The UES during a swallow is described as a grabber because it ascends to grab the bolus and then descends with it.
UES relaxation and opening also occur during belching, but the trajectory of movement of the cricoid cartilage and UES is different from the swallow. The UES moves mostly in the anterior direction during belching, suggesting that a different set of muscles are activated during these two events.
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The primary muscle of the UES is the cricopharyngeal part of the inferior pharyngeal constrictor
The upper esophageal sphincter (UES) is a high-pressure zone at the transition of the pharynx and the cervical esophagus. It is formed by the lower portion of the inferior pharyngeal constrictor, also known as the cricopharyngeal muscle or sphincter due to its relation to the cricoid cartilage of the larynx anteriorly. The UES is a 4-cm segment of the digestive tract consisting of cartilaginous, bony, and muscular components that opens and closes based on both intrinsic muscular control and displacement.
The LES surrounds the lower part of the esophagus at the gastroesophageal junction between the esophagus and the stomach. It is also called the cardiac sphincter or cardioesophageal sphincter, named for the adjacent part of the stomach, the cardia. The LES is a functional sphincter, meaning that it acts as a sphincter but does not have a distinct thickening like other sphincters. The intrinsic component of the LES consists of esophageal muscle fibres and is under neurohormonal control. The extrinsic component consists of the diaphragmatic crura and the phrenoesophageal ligament, which provide anatomical support to the LES and further protection against gastric reflux.
The UES and LES are two of the three anatomic constrictions encountered by the oesophagus. These areas of constriction are considered the most frequent sites for a foreign body or food impaction to occur. The UES and LES are both innervated by the vagus nerve and the cervical and thoracic sympathetic trunk. The vagus nerve has a parasympathetic function, supplying the muscles of the oesophagus and stimulating glandular contraction.
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The UES is controlled by intrinsic muscular control and displacement
The upper esophageal sphincter (UES) is a 4-centimetre segment of the digestive tract that separates the oesophagus from the pharynx and larynx. It is formed by the lower portion of the inferior pharyngeal constrictor, also known as the cricopharyngeal sphincter, due to its relation to the cricoid cartilage of the larynx. The UES is bounded anteriorly by the larynx, posterolaterally by the pharyngoesophageal muscles, superiorly by the pharynx, and inferiorly by the oesophagus.
The UES is a critical component of the airway protective mechanism. It controls the inflow and outflow through the region, preventing aerophagia in the anterograde direction and regurgitation in the retrograde. The UES is not under voluntary control. Instead, it opens and closes based on both intrinsic muscular control and displacement. The opening of the UES is triggered by the swallowing reflex, which involves the relaxation of the cricopharyngeus muscle (CPM), elevation of the larynx, and propulsion of the food bolus by the pharynx.
During swallowing, the UES opens to allow food to pass through to the oesophagus. The UES is a high-pressure zone at the transition of the pharynx and the cervical oesophagus. The UES works in coordination with the lower oesophageal sphincter (LES) to regulate the passage of food and liquids. The LES is located where the oesophagus meets the stomach and protects the oesophagus from the reflux of gastric contents. It is composed of intrinsic and extrinsic components. The intrinsic component of the LES consists of oesophageal muscle fibres and is under neurohormonal control. The extrinsic component consists of the diaphragmatic crura and the phrenoesophageal ligament, which provide anatomical support to the LES and further protection against gastric reflux.
The UES and LES are both functional sphincters that act to close the oesophagus when food is not being swallowed. The LES remains tonically contracted with an intraluminal pressure of about 30 mmHg at rest. When swallowing occurs, a peristaltic wave passes down the oesophagus, causing receptive relaxation of the LES, which allows for the easy propulsion of the swallowed bolus into the stomach. The LES must relax and open enough to allow the passage of food into the stomach.
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Frequently asked questions
The upper esophageal sphincter (UES) is a 4-cm segment of the digestive tract that separates the esophagus from the pharynx and larynx. The UES controls the flow of food and liquid into the esophagus.
The UES is composed of all skeletal muscles. The primary muscle of the UES is the cricopharyngeal part of the inferior pharyngeal constrictor.
The UES is not a true sphincter as it does not meet the definition of a sphincter, which is an annular muscle surrounding and able to contract or close a bodily opening. The UES is a combination of cartilaginous, bony, and muscular components that open and close based on both intrinsic muscular control and displacement.
