Intestinal muscularis in health and disease.

The intestinal muscularis is a multifunctional tissue that coordinates motility, immune responses, and tissue homeostasis through interactions among enteric neurons, smooth muscle cells (SMCs), and immune cells. Beyond its classical role in peristalsis, emerging evidence identifies the intestinal muscularis as an active regulatory hub integrating neural, immune, and microbial signals. Here, we review the anatomical organization, physiological functions, and pathological alterations in inflammatory bowel diseases, irritable bowel syndrome, infection, and Hirschsprung disease. We further highlight how disruption of integrated neuromuscular and immune networks drives pathological remodeling and discuss emerging concepts and future directions in muscularis biology.