Stabilizer Muscles
Stabilizing muscles are tiny muscles that surround the joints. Joints with a large range of movement such as the shoulders and hips tend to have more stabilizers than other, less mobile joints such as the fingers and spinal joints. The stabilizing muscles are there to offer support and stability (oddly enough) to the joints during movement, especially under load and during twists and turns.
An injury to a stabilizing muscle is important to treat with extra care to prevent future injury.