Anatomy and physiology of the colon: foundations for understanding constipation

Chronic constipation is one of the most prevalent gastrointestinal disorders worldwide and represents a major reason for medical consultation, with a substantial impact on quality of life and healthcare utilization. Traditionally, its evaluation has focused on symptom reporting and bowel movement frequency; however, this approach is insufficient to explain the marked clinical and pathophysiological heterogeneity observed among patients. The colon is a highly specialized organ with complex motor and sensory functions that rely on the integration of macroscopic anatomy, wall architecture, intrinsic neuromuscular systems, and visceral sensory mechanisms. Colonic physiology encompasses distinct motor patterns, including segmental activity and high-amplitude propagated contractions, as well as sensory processes responsible for detecting luminal distension and modulating perception of transit and defecatory urge. Disruption of any of these components may result in different constipation phenotypes, ranging from slow-transit constipation to defecatory disorders. In this context, a detailed understanding of colonic anatomy and physiology is essential for the appropriate interpretation of clinical and functional findings. The aim of this article is to integrate current scientific evidence on colonic anatomy and physiology and to highlight its relevance for understanding constipation from a pathophysiological perspective, with direct implications for clinical assessment and management.