Encapsulated nerve endings called mechanoreceptors are end components of afferent nerves and have specialized end organs surrounding the nerve terminal. Those receptors are concentrated in various human periarticular tissues. It is believed that these mechanoreceptors in the periarticular tissues are related to muscle reflexes. However, it is still unknown which type of mechanoreceptors contribute to the muscle reflexes and whether the mechanoreceptors excite and/or inhibit muscle activation. In the investigators previous studies, mechanoreceptors in the human proximal interphalangeal (PIP) joint and surrounding structures have been extensively examined. The investigators have identified that Pacini-like nerve endings in the PIP joint were found in substantial numbers in the junction of the C1 pulley and accessory collateral ligaments. The investigators hypothesize that the Pacini-like nerve endings in the junction of the C1 pulley generate activity in the associated flexor muscle/tendon in the finger.