Phalanges of the hand

The finger bones (Latin Ossa digiti manus ) are the knöchernden support elements of the fingers. In mammals, each fully trained finger has three bony support members as proximal phalanx, media and distalis ( " body-hugging, medium and body further phalange bones ", also phalanx I, II and III. ( AltGr phalanx " battle line of warriors ", " bole ", " roll " or "role" ) are referred to. the human thumb has only two phalanges. the connections between metacarpal and proximal phalanx and the phalanx bones to each other, the finger joints.

Structure in humans

The finger bones are typical of the structure of bones. It differs from close to the body (proximal ) to distally ( distal) phalanges base ( base phalanx ), body ( corpus phalanx ) and head (caput phalanx ).

The finger bone base of the proximal phalanx bears a concave articular surface for the metacarpophalangeal joint, the articular surfaces of the base of the lower phalange bones a sagittal guide comb. The articular surfaces of the head of proximal phalanx and media are called trochlea. The head of the end member is flattened and bears palm side ( palmar) roughness, the tuberosity of phalanx distalis manus, to which the retaining ligaments of the finger pads ( retinacula cutis ) attach.

Comparative Anatomy

The number of phalanx bone of each finger in humans ( 2-3-3-3-3 ) is the basic blueprint of mammals, in primitive reptiles we find the Phalangenformel 2-3-4-5-3. Stronger modifications within the mammals there are at the whales, in which additional phalanges are formed ( Hyperphalangie, Formula 2-12-8-1 ).

In ungulates the three phalanx bones are called bondage, Kron and coffin bone in the distal phalanx of predators is also called " claw leg". Back of hand side At the base of the phalanx media at the four-footed mammals an extension ( extensor process ) for preparation of the extensor digitorum lateralis and palm side, a roughness ( Tuberosits flexoria ) for preparation of the flexor digitorum superficialis.

The distal phalanx is due to the different first ground contact at the four-footed mammals marked differences to man. Here, a distinction is a joint surface ( articular facies ), a wall surface (facies parietalis ) and a sole surface (facies solearis ) in animal anatomy. At the articular surface of the distal phalanx an articular surface is for the navicular bone ( articular facies sesamoidea ). The plantar surface bears the attachment point for the flexor digitorum profundus, as the tubercle flexorium (ruminants, carnivores, pigs) or Facies flexoria ( horses) is called. At the front coronet, the processus rises to the extensor aspects of the extensor digitorum communis.

In birds, the little finger ( Digitus minor) and the Eckfittichfinger ( Digitus alulae ) only have a phalanx of big fingers ( Digitus major) has two phalanx bones.