Radius
The radial bone (lat. radius) is one of the two bones of the forearm. It belongs to the tubular bones and runs approximately parallel to the ulna. The radius is located on the thumb side of the forearm.
Anatomie
The radius is the somewhat more strongly developed bone of the forearm and lies approximately parallel to the ulna. With its long, narrow shape it belongs to the tubular bones. The radius is divided into the shaft (Corpus radii), one extremity proximal and one extremity distal.
Proximal end
At the proximal extremity there is the caput radii with the fovea articularis. The fovea articularis is a plate-shaped socket, which is framed by the Circumferentia articularis. This is where the connection to the humerus is located. Distally of the head of the ulna is the place with the smallest diameter, the collum radii. At the transition between collum radii and corpus radii, the tuberosity radii is located medially.
Radius shaft
The profile of the corpus radii has an almost three-sided shape. The Margo interosseus is medially directed, at this edge the Membrana interossea antebrachii is attached. It is located between the anterior and posterior facies. The lateral facies has a roughness of varying degrees in the middle third of the shaft, the pronator tuberosity, which is where the pronator teres muscle comes in. The lateral facies is separated from the posterior facies by the posterior margo.
Distal end
At the distal end (distal extremity) there is a bony protrusion, the stylus process (Processus styloideus radii). This is where the brachioradialis muscle begins. The distal end is thicker in its entirety than the shaft of the radius. On the medial side of the distal end is a notch, the incisura ulnaris. It is there for the head of the ulna. The widening distal end of the radius has the articulation surface Facies articularis carpalis. The carpal bones border on it.
Function
The radius forms a functional unit together with the ulna. The two bones form the basic bony structure of the forearm and give it stability. Together with the ulna, the radius is involved in the movements of the forearm and the hand.
Development
The radius shaft begins perichondral ossification as early as the seventh week of embryonic development. The distal epiphysis, on the other hand, is formed by the second year of life and the proximal one even by the seventh year of life. Between the ages of 14 and 17, complete closure of the epiphyseal fugues takes place.
