Due to blunt or penetrating trauma
The perinychium includes the nail, the nailbed, and the surrounding tissue.
The paronychia is the lateral nail folds
The hyponychium is the palmar surface skin distal to the nail.
The lunula is that white semi-moon shaped proximal portion of the nail.
The sterile matrix is deep to the nail, adheres to it and is distal to the lunule.
The germinal portion is proximal to the matrix and is responsible for nail growth.
Fingertip avulsion
Distal interphalangeal dislocation 
Ring avulsion injury
Distal phalanx 
Degloving injury
Finger amputation
Scapholunate dissociation
Toe fracture