The scapula is a flat, triangular bone which forms the back of the shoulder. People usually have two, one at either shoulder. These create the distinctive flat area on the upper back which people associate with the shoulder, and the scapula is sometimes known as the shoulder blade, in reference to its flat appearance and location. In species other than humans, the position is usually slightly different to allow for articulation of the front legs.
This bone connects with the clavicle or collarbone and humerus, also known as the arm bone. It also articulates with a number of different muscles involved in the movements of the arm and shoulder. Parts of the biceps, triceps, trapezius, and deltoid muscles, among many others, come into contact with the scapula.
Injuries to this bone are quite rare. This bone is very well protected, and when it is injured, it is usually as a result of blunt force trauma to the bone, a hard fall, or a severe chest injury. Cases in which the shoulder blade may be chipped or fractured include vehicle accidents, especially on motorcycles, and beatings in which the upper back is targeted. Less than one percent of broken bones are scapula fractures.
If the bone is fractured, it usually causes severe pain in the shoulder, and difficulty moving the associated arm. The fracture will show up on an x-ray. An orthopedic surgeon can examine the x-ray to determine the extent and precise location of the break. In some cases, it may be possible to treat a fracture with a sling to immobilize the arm while the fracture heals. In other instances, surgery may be required to pin the bone so that it can knit properly, and the patient may need to spend some time in the hospital until a surgeon is satisfied that the patient is out of danger.
Another problem is a condition known as winged scapula. In this case, the bone does not lie flat, instead protruding off the shoulder, causing it to look like someone has a small budding wing. Sometimes this problem can be treated with physical therapy to strengthen the muscles which anchor the bone so it will remain in place. In other cases, it may be necessary for the patient to undergo surgery to fix the improperly positioned bone, in which case the patient may be wearing a sling for several weeks while the surgical site heals.