指骨 - Ossa digitorum; Phalanges
The phalanges are fourteen in number, three for each finger, and two for the thumb. Each consists of a body and two extremities.
- The body tapers from above downward, is convex posteriorly, concave in front from above downward, flat from side to side; its sides are marked by rough which give attachment to the fibrous sheaths of the Flexor tendons.
- The proximal extremities of the bones of the first row present oval, concave articular surfaces, broader from side to side than from before backward.
- The proximal extremity of each of the bones of the second and third rows presents a double concavity separated by a median ridge.
- The distal extremities are smaller than the proximal, and each ends in two condyles separated by a shallow groove; the articular surface extends farther on the volar than on the dorsal surface, a condition best marked in the bones of the first row.
The ungual phalanges are convex on their dorsal and flat on their volar surfaces; they are recognized by their small size, and by a roughened, elevated surface of a horseshoe form on the volar surface of the distal extremity of each which serves to support the sensitive pulp of the finger.
Articulations.—In the four fingers the phalanges of the first row articulate with those of the second row and with the metacarpals; the phalanges of the second row with those of the first and third rows, and the ungual phalanges with those of the second row. In the thumb, which has only two phalanges, the first phalanx articulates by its proximal extremity with the metacarpal bone and by its distal with the ungual phalanx.
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