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Middle phalanges - hand
Other Terms:
Phalanx media manus
Type
long
Description
Like the metacarpal bones these bones are classified as having a proximal base, a narrowed shaft, and a distal head. These bones are easily identifiable by the similar articular surfaces at both base and head. The surfaces form a double concave articular surface limiting movement to the dorsopalmar plane. These bones are usually less than twice as long as their greatest width. The thumb does not have a middle phalanx.
Etymology
A Greek term that referred to a line of heavy-armed infantry drawn up in close order to do battle. The parallel digital rays resembled these lines of battle.
Articulations
The middle phalanges articulate with proximal phalanges and the distal phalanges. Their distal surface has a double concave articular face with a central spline. This spline limits the bone's movement with the proximal phalanx to the dorsopalmar plane. The head end of the middle phalanges forms a similar articular surface with the distal phalanges.
Ossification
The middle phalanges form a primary center in the mid-shaft region of the bone during the eleventh week of prenatal life. Secondary epiphyseal centers arise in the second year in females and in the third to fourth year in males. The epiphyses unite between the fifteenth and eighteenth year, typically earlier in females.
Latin
Phalanx media manus
