Bone · Shoulders

Scapula

Scapula

The scapula is the shoulder blade: a thin triangular plate that floats on the back of the ribcage held almost entirely by muscle — its only bony joint is a small one with the collarbone. That freedom is the point. It glides, tilts and rotates across the ribs so the arm can travel overhead, and it supplies the socket the arm bone sits in. The rotator cuff lives on its two faces, the trapezius, rhomboids and levator scapulae steer it from the spine, and the serratus anterior holds it flat against the ribs.