Scapula

The scapula sits on the back of your rib cage, floating on a cushion of muscle rather than attaching directly to the spine. It connects to the rest of the skeleton only through the clavicle (collarbone), via the acromioclavicular joint, and through the shoulder joint where it meets the humerus. This design gives the shoulder its huge range of motion.

Structurally, the scapula is a flat bone, with thin layers of cortical bone sandwiching a core of trabecular bone and marrow. Flat bones like this are built more for broad muscle attachment and protection than for heavy weight-bearing, which is the opposite of how long bones like the femur are loaded.

Scapula fractures are relatively uncommon compared to breaks in the hip, wrist, or spine, largely because the shoulder blade is well-protected by muscle and not a primary weight-bearing bone. When they do happen, it's usually from significant trauma, like a fall or car accident, rather than from everyday low-impact stress. A DEXA scan does not typically measure the scapula, since hip and spine sites give more useful fracture-risk information.