The application of MR imaging to examine the musculoskeletal system is widely practised. However, ultrasound is perceived as a dynamic, inexpensive alternative to the established but more expensive technique of MRI. This is a guide to the application of US. In a combined atlas and teaching file with over 800 images, this text presents correlative MR and ultrasound images to illlustrate how the two modalities - one commonly used in musculoskeletal exams, the other not - can be applied effectively to diagnose musculoskeletal ailments. The 12 major peripheral segments in the extremities (shoulder, arm, elbow, forearm, wrist, hand, hip, thigh, knee, leg, ankle and foot) are explored.