Phalanges
The phalanges are the bones that are found in the fingers and the toes. The phalanges of the hand are collectively known as the phalanges digitorum manus. The phalanges of the foot are collectively known as the phalanges digitorum pedis.
In the hand, the thumb has two phalanges: the distal phalange (farther from the wrist) and the proximal phalange (closer to the wrist or base of the finger). The remaining fingers add an intervening third phalange appropriately named the middle phalange. In total there are fourteen phalanges in the hand.
The phalanges of the hand are thickest at the end nearest the wrist, and narrow along their length. They are flat along their top and bottom surfaces, and their sides are rough in order to make the attachment of the flexor tendons easier. There is a great deal of articulation (movement of one bone relative to its neighbor) in the phalanges. This is one feature that allows the hand to be so dexterous. Often the phalanges are concave at the end that articulates with the next phalange. The convex portion of next phalange allows a smooth fit of one phalange with another.
Formation of the bones of the phalanges begins at about the eight week of fetal development for some of the phalanges. However, full development of the extreme phalanges is not complete until more than a year after birth, and development of all the phalanges is not complete until the end of the teenage years.
The number and arrangement of the phalanges of the foot is similar to those of the hand. The largest toe has two phalanges and the other toes have three phalanges. However, in the toe the phalanges are smaller, shorter and more compressed than those of the hand.
Other animals besides humans have phalanges. In the horse and the ox, as examples, the distal phalange is the bone of the hoof. In these animals the distal phalange is a single unit. There are not multiple distal phalanges, because horse and oxen do not, of course, have fingers.
Like all bones, phalanges are subject to breakage. Healing of a broken hand or foot bone involves the immobilization of the bone. In the hand, this can often take the form of a splint on the particular digit that has been damaged. In the foot, however, the entire foot is usually immobilized in a cast.
Some forms of disease strike preferentially at phalanges. Rheumatoid arthritis strikes at proximal phalanges while osteoarthritis generally affects distal phalanges. In either case, arthritis can debilitate the fingers and, over a period of time greatly decrease dexterity and function.
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