Bases of distal phalanges 2-5
The bones of the hand consist of the carpal bones, the metacarpal bones and the phalanges. The phalangeal bones of the hand are the terminal bones of the upper limb. Each finger of the hand possesses three phalangeal bones; a proximal phalanx, a middle phalanx and a distal phalanx, with the exception of the thumb which only possesses a proximal and a distal phalanx. This means that there are fourteen phalanges in total on each hand.
The proximal phalanges have long shafts and are flat on their palmar aspect. The middle phalanges are situated between the proximal and distal phalanges of the second to fifth fingers. The distal phalanges are the smallest of the phalangeal bones. They are tapered distally and possess a tuberosity at their distal ends. The palmar surfaces of the distal phalanges are especially rough as this is where the tendons of the flexor digitorum profundus muscle insert. The proximal bases of second to fifth distal phalanges articulate with the distal heads of the second to fifth middle phalanges, where as the base of the first phalanx articulates with the head of the first proximal phalanx.
A dislocation fracture of the distal phalanx is a common sports injury, often seen in sports such as volleyball or baseball. This type of injury is known as Mallet finger. A mallet finger injury occurs when a force of impact disconnects the distal phalanx from the middle phalanx. In some cases, the impact can also result in the rupture of the tendons that attach to the distal phalanx which can in turn result in the avulsion of small or large bone fragments within the tendon of the flexor digitorum profundus muscle.
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