The forearm primarily has two different bones: the radius and the ulna. The forearm bones are characteristically long and thin. There is also a noticeable gap in between the bones, where a sheet of fiber called the interosseous membrane is located.
A part of the human upper limb, the forearm bones are situated from the elbow down to the wrist. The bone is parallel to the leg part of the human lower limb, from the knee to the ankle. One can determine the radius from the ulnar bone by holding the hand facedown. The radius bone stretches from where the thumb is located, while the little finger is the indicator for where the ulnar bone is.
The radius is the shorter bone of the two forearm bones; it is arched to a small extent and has a shape like a prism. One end of the radius bone directly communicates with the other end of the humerus bone of the upper arm, which partly creates the elbow joint. The other end is connected to the smaller bones and joints that make up the wrist. In this end, the radius also connects with the ulnar bone sideways, forming a triangle of sorts with the wrist bones. The main function of the radius is to help facilitate the movement of the wrist, as it directly connects with the latter. The upper part of the bone nearer the elbow also serves as a point of attachment for the biceps muscles.
The ulnar bone defeats the radius bone in terms of length, but shares the same prismatic shape. One end of this bone completes the structure of the elbow, together with the ends of the radius and the humerus bones. Unlike the radius, the ulna has no direct connection with the wrist joint and, therefore, does not have any function in moving the hand and wrist. It is, however, directly linked with the upper arm and is the point of attachment of the triceps muscle, the lower muscles of the upper arm.
Between the two forearm bones, the radius bone is more prone to fracturing as compared to the ulnar bone, especially in martial arts. One standard technique in defending a fighter’s head is to raise the arms and block the strike. In this position, the radius bone collides with the opponent’s strikes and suffers more injuries. In childhood forearm fractures, three children out of four also experience radius fractures, as opposed to one out of four children encountering ulnar fractures.