Anatomy of the wrist and metacarpus

The wrist is made of many bones so that if damage occurs, it does not spread to the entire joint. The wrist has seven bones and one accessory bone. As for the seven main bones, they are located in two rows. One row is adjacent to the forearm and has three bones. Since it is adjacent to the forearm, it should be narrower. There are four bones in the second row; since this row is adjacent to the metacarpus and fingers, it should be wider. The three bones of the first row gradually thicken; their heads adjacent to the forearm are narrower, and they are located closer and more tightly connected, while the heads adjacent to the other row are wider; they are not so closely spaced and less tightly connected.

As for the eighth bone, it does not participate in strengthening the two rows of the metacarpus and is created to protect the nerve adjacent to the palm. The triple row has an edge formed due to the connection of the heads of its bones; this end enters the hole we mentioned at the end of both “flints”, due to which an articulation is formed that carries out extension and flexion. The above-mentioned process in the lower “flint” enters a fossa in the adjacent carpal bones; Thanks to this, an articulation is formed that carries out pronation and supination.

The metacarpus also consists of several bones so that if damage occurs, it does not spread to all the bones and so that the hand can form a depression in the palm when holding round objects, and also so that liquids can be held in the palm. The joints of these bones are motionless and the bones are fastened together so that they do not move apart and the hand does not become too weak to hold objects. If you peel the skin off your hand, you will find that all these bones merge, and their joints are invisible. In this case, the ligaments firmly attach them to each other, but they can still move slightly closer together, so that a depression is formed on the inside of the hand.

There are four metacarpus bones, as they are adjacent to the four fingers. On the side adjacent to the wrist, they come together in order to connect well with the bones, which are, as it were, fused and connected to each other, and in the direction of the fingers they diverge slightly in order to connect well with the bones that are diverging and separated from each other. On the inside they are concave for a reason that you already know. The articulation of the metacarpus with the wrist occurs through the pits at the ends of the carpal bones, into which the projections of the metacarpal bones, covered with cartilage, enter.