Fasciae of the musculoskeletal system: normal anatomy and MR patterns of involvement in autoimmune diseases

The fascial system is a three-dimensional continuum of connective tissues present everywhere throughout the body, from the head to the toes and from the skin to the bone. The current article aims to review the normal anatomy of the fasciae of the musculoskeletal system with macroscopic and microscopic correlations and to describe their appearance at MRI in normal subjects and in patients with autoimmune diseases of the musculoskeletal system. Key Points • The fascial system is a three-dimensional continuum of connective tissues. • It is present everywhere throughout the body, from the head to the toes and from the skin to the bone. • The normal fascial system is barely visible at MRI. • MR patterns of fascial involvement in autoimmune diseases reflect the complex anatomy of the fasciae of the musculoskeletal system.