Tendons are a strong band of fibrous connective tissues that link the muscle to the bone. These tendons are protected by another layer of connective tissues called the tendon sheaths. When the tendon sheaths on the finger are inflamed , the normal gliding motion of the tendon through the tendon sheath is disrupted. When the tendon sheath is irritated or inflamed for a long period, the tendons can be scarred , thickened and may develop bumps or nodules . This can interfere with the tendons' movement, which can lead to stiffness and pain in the finger , a condition known as trigger finger. While the causes of trigger finger are not always clear, they may include: Rheumatoid arthritis Gout Diabetes Injury to the palm or base of the finger