Thumb Bone Structure. All the fingers have 3 phalanges except the thumb which has 2 phalanges. Anatomically the thumb is compromised of the metacarpal connected to the trapezium a carpal bone in the wrist.
The thumb has two of each. The first metacarpal is properly connected to the proximal phalanx. The diaphysis and the epiphysisThe diaphysis is the tubular shaft that runs between the proximal and distal ends of the bone.
The CMC joint of the thumb is located at the junction point of the thumb and the wrist.
The three joints are as follows. The interphalangeal IP joints are the finger joints. Each phalanx in a finger is named according to its location. Causes for a swollen thumb can arise from a bacterial infection within the nail trauma from a injury that is affecting the thumb bones or inflammation of the thumb joints.
