Generality
A metacarpal, or metacarpal bone, is one of the 5 long bones that, in each hand, are placed between the carpal bones and the proximal phalanges of each finger (see figure).
The traditional denomination of the 5 metacarpals requires the use of the first 5 Roman numerals. From this it follows that: the metacarpal bone is the metacarpal bone that precedes the phalanges of the thumb, the second metacarpal is the metacarpal bone that precedes the phalanges of the thumb. "index, the III metacarpal is the" metacarpal bone placed before the phalanges of the middle and so on.
The metacarpals are the insertion site for some important muscles and some ligaments of the hand.
Like any bone in the human skeleton, the metacarpals can also be fractured.
What is a metacarpal?
A metacarpal, or metacarpal bone, is one of the 5 long bones that, in each hand, are positioned between the carpus - that is, the bony part of the wrist and the base of the hand - and the proximal phalanges (or first phalanges) of each finger .
In a human hand, the metacarpals are 5 of the 27 total bones (8 carpal bones, 5 metacarpal bones and 14 phalanges).
Review of the meaning of the terms proximal and distal
Proximal and distal are two terms with opposite meanings.
Proximal means "closer to the center of the body" or "closer to the point of" origin. Referring to the femur, for example, it indicates the portion of this bone closest to the trunk.
Distal, on the other hand, means "farther from the center of the body" or "farther from the point of origin". Referred (always to the femur), for example, indicates the portion of this bone farthest from the trunk (and closest to the knee joint).
Figure. Bones of the hand. The 8 carpal bones make up a structure called the carpus. The carpus takes part in the important articulation of the wrist. The 14 phalanges make up the skeleton of the 5 fingers of each hand: except the thumb, which is the only finger formed by 2 phalanges, all the other fingers have 3 phalanges each. The phalanges closest to the metacarpals are called first phalanges (or proximal phalanges); starting from these, the following ones are called, respectively, second phalanges (or intermediate phalanges) and third phalanges (or distal phalanges) *. * N.B: in the case of the thumb, the numbering ends with the second phalanges.
In each metacarpal, three portions are distinguishable:
- A central portion, called the body;
- A portion at the proximal end, called the base;
- A portion at the distal end, called the head.
Between the so-called base and the so-called head, the body of each metacarpal is a cylindrical and elongated portion, with the important task of inserting the so-called interosseous muscles of the hand.
The base of each metacarpus is the slightly lumpy portion, bordering and forming a joint with a carpal bone (or carpal bone). In the human hand, the various metacarpals border on different carpal bones, depending on the position they occupy.
Finally, the head of each metacarpus is the portion which is also moderately lumpy, connected and articulated to a specific proximal phalanx of the fingers. From this, it follows that each first phalanx of the hands is preceded by a precise metacarpus.
By convention, the 5 metacarpals are indicated with the first 5 Roman numerals, that is I (first), II (second), III, IV and V. proximal phalanx of the thumb; the metacarpus indicated by the number II (II metacarpal) is the metacarpal bone preceding the proximal phalanx of the index finger; the metacarpal marked with the number III (III metacarpal) is the metacarpal bone preceding the first phalanx of the middle finger; the metacarpal identified with the number IV (IV metacarpus) is the metacarpal bone preceding the proximal phalanx of the ring finger; finally, the metacarpal indicated by the number V (V metacarpal) is the metacarpal bone that precedes the first phalanx of the little finger.
Again by convection, the metacarpus considered more lateral is the first metacarpus (that of the thumb), while the metacarpus considered more medial is the fifth metacarpus (that of the little finger).
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