At the shoulder joint, you can perform active rotation of the humerus and this too is described as adjunct rotation. Adjunct rotation is often referred to as voluntary rotation as it is produced by muscle action. Conjunct rotation is a term used to describe a small amount of rotation that occurs at a joint during, for example flexion and extension. The term comes from the Latin conjunctus - meaning joined together . Conjunct rotation movements are automatic and inevitable, they are caused by the influences of the ligaments around the joint and the shape of the joints surfaces.
Conjunct rotation occurs with both active and passive movements.
A good example of conjunct rotation is seen in the knee joint. About 30 of lateral rotation occurs from full flexion to full extension. However, if you were to stand up from a chair and your feet were planted firmly on the floor, then your tibia could not rotate as your knee extended.