Toe bones

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Scheme of human foot bones.

The toe bones ( lat. Ossa digiti pedis or Ossa digitorum pedis ) are the bony supporting elements of the toes . In mammals , every fully developed finger has three bony support elements, which are called the phalanx proximalis , media and distalis ("near, middle and distal phalanx bones"), also phalanx I, II and III (from the old Greek phalanx "battle row of warriors" "tree trunk", "Roller", or "roller"). The big toe has only two phalanges, the middle one is not formed. The connections between the metatarsal bones and the proximal phalanx and the phalanx bones are the toe joints .

Structure in humans

The structure of the toe bones is typical of tubular bones and is similar in structure to the finger bones . A distinction is made between body (proximal) and distal toe bone base ( base phalangis ), body ( corpus phalangis ) and head ( caput phalangis ).

The base of the toe bones of the phalanx proximalis bears a concave joint surface for the metatarsophalangeal joint , the joint surfaces of the base of the lower phalanx bones a sagittal guide comb. The articular surfaces of the head at the proximal and media phalanx are known as the trochlea . The head of the distal phalanx is flattened and has a roughness on the foot surface ( plantar ), the tuberosity phalangis distalis pedis .

X-ray of the toe bones

On the sole side of the first metatarsophalangeal joint in humans, there are two small sesamoid bones that are embedded in the tendons of the abductor hallucis and adductor hallucis muscles .

Comparative anatomy

In ungulates the three phalange bones as are pastern ( Os compedale ), crown- ( Os coronal ) and coffin bone ( Os ungulare ) refer to operations predators the distal phalanx (also known as "claw leg" is unguiculare Os ), respectively. The wolf's claw , which is usually not present in dogs - the rudiment of the first toe - has only one phalange.

In ruminants, at the base of the phalanx media of the fourth toe, on the dorsal side of the foot, is the attachment point of the extensor digitorum lateralis muscle . On the side of the foot surface, all quadruped mammals have a roughness on the middle phalanx of the supporting toes ( tuberosits flexoria ) for the attachment of the superficial toe flexor .

The phalanx distalis shows clearer differences to humans due to the different footing in the quadruped mammals. In animal anatomy, a distinction is made between a joint surface ( facies articularis ), a wall surface ( facies parietalis ) and a sole surface ( facies solearis ). An articular surface for the navicular bone ( facies articularis sesamoidea ) is located on the joint surface of the phalanx distalis . The sole surface carries the attachment point for the flexor digitorum profundus , as flexorium tubercle (ruminants, carnivores, pigs) or facies flexoria (horse) is called. At the anterior coronet the processus extensorius (called crista unguicularis in predatory animals ) rises to the insertion of the musculus extensor digitorum longus .

In birds , the number and position of the toe bones vary (→ bird's foot ). The number of phalanges is always one greater than the ordinal number of the corresponding toe: The first toe has two phalanges, the second toe three, and so on.

See also


Walther Graumann, Rolf Baur: Compact textbook anatomy . Schattauer Verlag 2004, ISBN 978-3-79452062-6 .

Individual evidence

  1. ^ A b Franz-Viktor Salomon: Musculoskeletal system . In: Franz-Viktor Salomon et al. (Hrsg.): Anatomie für die Tiermedizin . Enke-Verlag, Stuttgart 2. Erw. 2008 edition, pp. 22-234. ISBN 978-3-8304-1075-1