Gastric Motility and Emptying

Gastric motility is the coordinated muscular activity of the stomach that receives, stores, mixes, and then delivers a meal to the small intestine. Gastric emptying is the rate-controlled output of that process: the stomach relaxes to accommodate food, grinds solids into small particles, and meters chyme into the duodenum at a pace matched to downstream digestion.

Definition

Gastric motility and emptying refer to the regulated motor activity by which the stomach accommodates a meal, mixes and grinds its contents, and delivers chyme to the duodenum at a controlled rate, together with the assessment of how fast that emptying occurs.

Scope

This topic covers the normal motor functions of the stomach — receptive relaxation, accommodation, trituration, and regulated emptying — and how delayed emptying is recognised conceptually. It is a reference and educational entry on gastric motor physiology and its measurement; it does not provide management protocols for any disorder of emptying.

Core questions

• How does the stomach accommodate, mix, and empty a meal?
• What neural and hormonal signals control the rate of gastric emptying?
• How is gastric emptying measured objectively?

Key concepts

• Receptive relaxation and gastric accommodation
• Antral trituration (grinding)
• Gastric pacemaker and slow waves
• Migrating motor complex
• Liquid versus solid emptying
• Gastric emptying scintigraphy
• Delayed emptying (gastroparesis)

Mechanisms

The proximal stomach relaxes as food arrives (receptive relaxation and accommodation), serving as a reservoir, while the distal stomach contracts to grind solids against a closed pylorus until particles are small enough to pass (trituration). These contractions are organised by gastric slow waves generated by interstitial cells of Cajal acting as a pacemaker, modulated by vagal and enteric neural input and by hormones such as those signalling fullness. Liquids empty in a roughly exponential pattern and solids after a lag phase once triturated; between meals the migrating motor complex sweeps residual material onward. Emptying rate is commonly quantified by gastric emptying scintigraphy, and its delay without mechanical obstruction defines gastroparesis.

Clinical relevance

Normal gastric motility is the reference against which disordered emptying is understood; when emptying is delayed without obstruction, the result is the symptom complex of gastroparesis, and when it is disordered in other ways it contributes to functional dyspepsia. This entry describes the physiology and its assessment for reference and education and is not a guide to managing any individual.

History

Understanding of gastric motor function progressed from radiographic and intragastric pressure studies to electrophysiological description of gastric slow waves and the pacemaker role of interstitial cells of Cajal, and to standardised gastric emptying scintigraphy, which gave the field a reproducible measure that underpins the modern definition of delayed emptying.

Key figures

• Michael Camilleri
• Henry P. Parkman

Seminal works

• camilleri-2013-acg
• camilleri-2022-acg

Frequently asked questions

How does the stomach empty a meal?

The upper stomach relaxes to store food, the lower stomach grinds solids into small particles against the pylorus, and chyme is then metered into the duodenum at a controlled rate; liquids empty faster than solids.

How is gastric emptying measured?

The standard objective test is gastric emptying scintigraphy, which tracks a radiolabelled meal over time; delayed emptying in the absence of a mechanical blockage is the basis for diagnosing gastroparesis.