Mallet finger is a condition where the end of the finger is bent and does not straighten. It occurs when the extensor tendon on the back of the finger is damaged. The finger joint is a hinge-joint that allows bending and straightening of the fingers. Each finger is composed of 3 phalanges joined by 2 interphalangeal joints (IP joints).
Tendons in your fingers connect the finger bones to finger muscles and help bend and straighten the finger at the joint when the muscles contract. Boutonnière deformity is a condition in which a tendon injury to the middle joint of the finger results in the inability to straighten the affected finger.
A nail is the hard covering at the end of the dorsal side of your fingers and toes. The nail is composed of a nail plate, nail matrix (a tissue that protects nails) and nail bed. The nail plate is a hard, translucent part of the nail composed of a protein called keratin. The nail bed is the skin that is present below the nail plate. Nail bed injuries are very commonly associated with hand injuries or fingertip injuries.
Metacarpophalangeal Joint Arthritis