Ruga

Ruga is the singular form of rugae, a term used in anatomy to describe a fold or ridge in a mucous membrane or organ. The word is commonly applied to several specialized ridges found in the human body, and more generally to folds in various mucosal tissues.

In the stomach, gastric rugae are prominent folds of the mucosa and submucosa that allow the organ to expand after eating. When the stomach is empty, the rugae are pronounced; as the stomach fills, they flatten to accommodate the volume. Their structure includes mucous glands and submucosal tissue, reflecting both form and function in digestion.

Another well-known set are the rugae palatinae, the transverse ridges on the hard palate. These ridges help with the manipulation of food inside the mouth and contribute to the texture and grip needed for speech and swallowing.

Beyond these examples, the term ruga is used more broadly to denote folds on other mucosal surfaces. The pattern and prominence of rugae can vary with development, nutrition, and health, and notable changes can be observed in certain medical conditions that affect mucosal structure.

Etymology wise, ruga derives from Latin ruga, meaning a fold, crease, or wrinkle. The term is used across anatomical contexts to describe similar ridged or folded patterns on tissues and organs.