Shoulder Anatomy Explained

Understanding shoulder anatomy helps explain how the arm achieves such a large range of movement and why shoulder pain and injuries can develop. The shoulder is one of the most mobile regions of the body, allowing us to reach, lift, push, pull and rotate the arm through a remarkable range of movement. But the shoulder is not simply one joint. It is a complex system of bones, joints, muscles, tendons, ligaments and other structures working together to produce movement while maintaining stability.

In this guide, we’ll explore the anatomy of the shoulder, how its different structures work together and why understanding them can help make sense of common shoulder problems.

The Shoulder at a Glance

The shoulder is often described as a ball-and-socket joint, but this is only part of the picture. What we commonly call the shoulder is a group of joints and structures that work together to position and move the arm.

The main bones involved are the humerus (upper arm bone), scapula (shoulder blade) and clavicle (collarbone). These bones interact through several joints, while muscles, tendons, ligaments and other soft tissues help provide movement, control and stability.

The Bones of the Shoulder

Three bones form the main framework of the shoulder: the humerus, scapula and clavicle. Their shape and relationship to one another allow the arm to move through a large range while providing attachment points for the muscles and ligaments that control the shoulder.

Humerus

The humerus is the bone of the upper arm. Its rounded head forms the “ball” of the shoulder’s main ball-and-socket joint, articulating with the glenoid of the scapula.

Scapula

The scapula, or shoulder blade, is a flat triangular bone that sits on the back of the rib cage. It contains several important landmarks, including the glenoid, acromion and coracoid process, and provides attachment for many of the muscles involved in shoulder movement.

Clavicle

The clavicle, or collarbone, connects the shoulder to the chest through the sternoclavicular joint. It acts as a strut that helps position the shoulder away from the body and transfers forces between the arm and trunk.

The Joints of the Shoulder

Three bones form the main framework of the shoulder: the humerus, scapula and clavicle. Their shape and relationship to one another allow the arm to move through a large range while providing attachment points for the muscles and ligaments that control the shoulder.