The “wings on your back” are actually your shoulder blades, scientifically known as the scapulae. The term “scapula” comes from a Classical Latin word resembling a trowel or small shovel, which describes its flat, broad shape. People often notice these bones when they move their arms, as they become more prominent.
The Scapula: Your Shoulder Blade
The scapula is a flat, triangular bone positioned on the posterolateral aspect of the thoracic cage, typically resting over ribs two through seven. It is a primary component of the pectoral (shoulder) girdle, connecting the upper limb to the axial skeleton. Each scapula is paired, with one on either side of the body, acting as a mirror image.
The scapula articulates with two bones to form the shoulder joint complex. The glenoid fossa, a shallow depression on the scapula’s lateral angle, connects with the head of the humerus (upper arm bone) to form the glenohumeral joint. Additionally, the acromion, a projection extending from the scapular spine, articulates with the clavicle (collarbone) at the acromioclavicular (AC) joint. This bony structure provides attachment points for 17 muscles, contributing to shoulder stability and mobility.
How Shoulder Blades Enable Movement
The shoulder blades enable a wide range of motion in the arms and shoulders. They do not directly articulate with the rib cage in a bony joint but rather glide and rotate over it, forming the scapulothoracic joint. This unique arrangement allows for extensive movement in multiple directions, including elevation (moving upward), depression (moving downward), protraction (moving forward and away from the spine), and retraction (moving backward and toward the spine).
Numerous muscles attached to the scapula facilitate these movements. For instance, the trapezius, serratus anterior, and rhomboid muscles work together to control the scapula’s position and movement during activities like lifting, reaching, pushing, and pulling. When you raise your arm overhead, the scapula rotates upward, tilts posteriorly, and externally rotates, providing a stable base for the humerus. This complex interplay allows the shoulder joint to achieve its full range of motion while maintaining stability.
Supporting Your Shoulder Blade Health
Maintaining shoulder blade health involves mindful daily habits and body mechanics. Good posture is important, as slouched or rounded shoulder positions can alter the scapula’s alignment and strain surrounding muscles. Keeping your shoulders back and down, with a neutral spine, helps support the natural positioning of the scapulae.
Regular movement and avoiding prolonged static positions also contribute to scapular well-being. Engaging in activities that encourage the scapulae to move through their full range can help maintain muscle balance and prevent stiffness. Understanding the role of your shoulder blades in arm movement promotes better overall shoulder health.