Upper esophageal sphincter

Definition

The upper esophageal sphincter (UES) is a ring of skeletal muscle located at the top of the esophagus. It controls the passage of food and liquids from the pharynx into the esophagus.

5 Must Know Facts For Your Next Test

1. The UES is composed primarily of cricopharyngeus muscle.
2. It remains closed to prevent air from entering the esophagus during breathing.
3. The UES opens reflexively during swallowing to allow food to pass into the esophagus.
4. Dysfunction of the UES can lead to conditions such as dysphagia or aspiration.
5. Pharmacological agents that affect muscle tone can influence UES function.

Review Questions

• What type of muscle primarily composes the upper esophageal sphincter?
• Why does the upper esophageal sphincter remain closed when not swallowing?
• How can dysfunction in the upper esophageal sphincter present clinically?

Related terms

Lower Esophageal Sphincter: A ring of smooth muscle at the junction between the esophagus and stomach, preventing acid reflux.

Dysphagia: Difficulty in swallowing, which can involve problems with the UES.

Cricopharyngeus Muscle: A key component of the upper esophageal sphincter involved in controlling its opening and closing.