Esophageal Motility

Esophageal motility is the coordinated muscular activity that transports a swallowed bolus down the esophagus to the stomach. After the upper esophageal sphincter admits the bolus, a wave of circular muscle contraction (peristalsis) sweeps it aborally, and the lower esophageal sphincter relaxes to allow it to enter the stomach. The cervical esophagus is striated muscle driven by vagal motor neurons, while the smooth-muscle esophagus is coordinated by the enteric myenteric plexus.

Definition

Esophageal motility is the patterned contraction and relaxation of the esophageal muscle layers and sphincters that propels a swallowed bolus from the pharynx to the stomach, chiefly through peristalsis and coordinated sphincter relaxation.

Scope

This topic covers the normal motor physiology of the esophageal body and its sphincters: primary and secondary peristalsis, the transition from striated to smooth muscle, the neural control of contraction, and the relaxation of the lower esophageal sphincter. It introduces high-resolution manometry as the modern tool for describing esophageal motor function, but it does not address the diagnosis or treatment of motility disorders.

Core questions

• How does peristalsis propel a bolus through the esophagus?
• What is the difference between primary and secondary peristalsis?
• How do the striated and smooth-muscle portions of the esophagus differ in their control?
• How is the lower esophageal sphincter relaxation coordinated with the peristaltic wave?

Key concepts

• Primary peristalsis
• Secondary peristalsis
• Striated versus smooth muscle esophagus
• Vagal control of the striated esophagus
• Myenteric plexus and the smooth-muscle esophagus
• Deglutitive inhibition
• Lower esophageal sphincter relaxation
• High-resolution manometry

Mechanisms

When a swallow is initiated, a primary peristaltic wave begins in the pharynx and travels the length of the esophagus as a sequential circular-muscle contraction that pushes the bolus ahead of it. The striated cervical esophagus is driven directly by vagal motor neurons firing in the appropriate sequence, whereas the smooth-muscle esophagus is governed by the myenteric plexus: excitatory and inhibitory neurons create a gradient of latency so that contraction proceeds from proximal to distal, a pattern in which an initial wave of deglutitive inhibition precedes the contraction. Distension of the esophagus that is not cleared by a primary wave triggers secondary peristalsis, a locally generated wave that clears residual material. As the wave approaches the gastroesophageal junction, the lower esophageal sphincter, which is tonically contracted at rest, relaxes to allow the bolus into the stomach and then regains its tone.

Clinical relevance

Normal esophageal motor physiology is the baseline against which esophageal motility disorders are characterized using high-resolution manometry and consensus criteria. This entry describes how the normal esophagus moves a bolus and how that motion is measured; it is reference material and not a basis for diagnosing or treating motility disorders in any individual.

Evidence & guidelines

The physiology summarized here is based on reviews of normal esophageal motility, while high-resolution manometry and its consensus interpretation, the Chicago Classification, provide the standardized framework now used to describe esophageal motor patterns and define abnormal motility.

Seminal works

• goyal-chaudhury-2008
• yadlapati-2021

Frequently asked questions

What is the difference between primary and secondary peristalsis?

Primary peristalsis is the wave triggered by a swallow that travels the whole esophagus, whereas secondary peristalsis is a locally generated wave triggered by esophageal distension that clears any residual bolus not moved by the primary wave.

Why are the upper and lower parts of the esophagus controlled differently?

The upper, striated-muscle esophagus is driven directly by vagal motor neurons, while the lower, smooth-muscle esophagus is coordinated by the enteric myenteric plexus, which sets up the timing gradient that produces an orderly peristaltic wave.