The large, flat, triangular-shaped bone at the back of the shoulder is called a shoulder blade. This bone, medically known as the scapula, is at the top of the back, behind each shoulder. It is thought that the word "scapula" came from the Greek word skaptein, which means “to dig." In early Roman times, people thought the bone resembled a trowel, a small shovel. The shoulder blade is also called omo in Latin medical terminology.
The shoulder blade lies over the second through seventh ribs on each side of a person’s back. It forms part of the pectoral girdle and helps connect the arm with the chest area. Specifically, it connects the arm bone, the humerus, with the collar bone, the clavicle. The scapula is a flat bone, so it has a large area for muscle attachment. There are 18 muscles that are attached to various parts of the scapula, either by insertion or by origin points.
The shoulder blade and the scapular muscles that are attached to it have many movements, such as depression, elevation, retraction, protraction, lateral rotation, upward rotation, medial rotation, downward rotation, posterior tipping and anterior tipping. Injuries to this area typically come in the form of pulled muscles, because of the large number of muscles that are attached to it. The shoulder blade is a very sturdy structure in a very protected location, which makes fractures uncommon. When the scapula does break, it usually is a sign of severe trauma.
When a child is born, some of the outer parts of the shoulder blade are cartilaginous. The bone then undergoes endochondral ossification and hardens. Most of the scapula has a thin layer of compact tissue, and the process, head and other thickened parts have spongy tissue. Some parts of the shoulder blade are so thin in humans that they are semitransparent, and the adjacent muscles are separated by fibrous tissue.
In ancient times, people would use the scapula from a large animal as a shovel. The dip in the middle of the animal's scapula could hold dirt or any other substance that is being dug up. This bone also could be crafted into a crude tool for cutting and chopping.