shoulder blade

Meaning of shoulder blade: A flat, triangular bone on the upper back, the shoulder blade anchors many of the muscles that stabilize and move the arm.

Definition of shoulder blade

The shoulder blade is a flat, triangular bone situated on the upper back, one on each side, forming part of the shoulder region. It has a shallow socket on its outer edge, called the glenoid cavity, which meets the rounded head of the upper arm bone to form the main shoulder joint, and a bony ridge across its back where it also connects to the collarbone at a smaller joint near the tip of the shoulder.

The shoulder blade lies against the rib cage but is not rigidly attached to it, instead being held in place by a group of surrounding muscles, including the muscles of the rotator cuff, which stabilize the shoulder joint and control much of the arm's range of motion.

Because the shoulder blade depends on muscle attachments rather than a fixed bony connection to the rib cage for its position, damage to one of the nerves supplying those muscles can allow the bone to shift abnormally, a finding sometimes described as a winged appearance of the shoulder blade.