Adduction is an anatomical term that refers to a joint movement in which a limb that has been raised to the side of the body is pulled back inward toward the midline of the body. An example of this action at the shoulder joint is pulling an arm that has been lifted laterally to shoulder height back in toward the body. Joints that can be adducted, such as the shoulder, hip, wrist, and ankle joints, can also perform abduction, which is the lifting of the limb away from the midline of the body as in raising the arm sideways to shoulder height. True adduction is said to occur in the frontal plane, which is the vertical plane of motion that divides the body into front, or anterior, and back, or posterior, sections.
In anatomy, joint movements such as flexion and extension, adduction and abduction are described relative to anatomical position. Anatomical position is a position of neutral alignment and a point of reference for defining movements. It describes the body in a standing position with feet hip-width apart and toes pointing straight ahead, pelvis neither arched back nor tucked under, arms down at sides with palms facing forward, and chin neither tilted down nor up. Relative to anatomical position, therefore, abduction of the hip would be the raising of the leg to one side without rotating the hip open, so that the toe remains pointed forward. Adduction, on the other hand, is the returning of the abducted leg to anatomical position.
The two joints that can perform the largest range of abduction and adduction are the shoulder and hip joints. Muscles responsible for adducting the shoulder or glenohumeral joint include the subscapularis and infraspinatus muscles of the rotator cuff and the teres major muscle, found on either side of the back just below the armpit. Other muscles involved in shoulder adduction include the pectoralis major in the chest and latissimus dorsi in the back. Exercises that adduct the shoulder joint include the decline chest fly as well as the chin-up and lat pull-down — all exercises that involve drawing the arms downward and inward toward the sides.
Muscles responsible for adduction of the hip or acetabulofemoral joint are the adductors longus, brevis, and magnus — all found along the inner thigh. Other hip adductor muscles include the pectineus and gracilis muscles, found in the groin and inner thigh, respectively. Hip adduction exercises include the side lunge as well as the hip adductor machine found in most health clubs, in which the exerciser sits in a seat with legs extended forward and spread open and inner thighs pressed against leg pads. She then squeezes the thighs together to contract the adductors and lift the weight.