Adductor muscles are any muscles in the body that causes adduction, which is the movement of a joint towards the center of the body. Though the term can refer to muscles that adduct the shoulder, wrist, or ankle, "adductor muscles" generally refers to a set of muscles that are found on the inner part of the thigh — hip adductor muscles. There are four hip adductor muscles: the adductor brevis, longus, magnus, and minimus. All of these adductor muscles function to to pull the leg towards the center of the body as well as provide stability to the hip.
The adductor brevis is called a short adductor, as it attaches from the hip to the thigh bone, rather than from the hip to the knee. The main function of this adductor muscle is to adduct the hip — that is, bring the hip in towards the pelvis. The muscle is also involved in hip flexion or hip flexing — i.e., bringing the knee upward.
Another short adductor is the adductor longus. As the name suggests, this is a bigger muscle than the adductor brevis, and therefore attaches to the thigh bone further down the leg. It is also involved in adduction and flexion of the hip.
Unlike the brevis and longus, the adductor magnus attaches to the inside of the knee. For this reason, it is called a long adductor. The muscle has two parts: the adductor and hamstring heads. While the adductor part of the muscle helps to adduct the hip, the hamstring part is involved in hip extension.
The smallest of the four adductor muscles is the adductor minimus. It is a flat muscle that attaches to the thigh bone. In addition to adducting the hip, this muscle helps correct misalignment of the leg.
Two other muscles involved in adduction of the hip: the pectineus and gracilis. These are not usually referred to as true adductors, but are commonly included in the adductor group. The muscles work closely with the rest of the adductors to provide adduction of the hip.
The pectineus is located at the top of the thigh. Like the adductor brevis and longus, it plays an important role in both adduction and flexion of the hip. Unlike the two short adductors, however, it is attached to the nervous system via the femoral nerve, rather than the obturator nerve.
Like the adductor magnus, the gracilis runs from the hip all the way down the inside of the leg to the knee. It is an important muscle that helps with knee flexion as well as hip adduction. This muscle is commonly injured in what is often referred to as a groin strain.