The human forearm is comprised of two major bones that span from the elbow joint to the wrist joint: the ulna and the radius. Specifically, the radius, also known as the radial bone, originates from the lateral side of the elbow and extends towards the thumb side of the wrist. This essential bone connects with the capitulum of the humerus at the elbow and forms a connection with the ulna at the radial notch. Additionally, at the wrist, the radius and ulna come together once again, creating the wrist joint.
Structure of the Radius Bone
The radius bone is classified as a long bone due to its elongated shape, being longer than it is wide. It is relatively smaller and shorter compared to the ulna bone. The radius consists of a central shaft or body and two distinct ends. Within the shaft, there is a slender and elongated medullary cavity, surrounded by a dense layer of compact bone tissue. This medullary cavity contains yellow bone marrow, which serves as a storage site for triglycerides, providing energy for the body. Additionally, the walls of the medullary cavity are composed of spongy bone, which reinforces its strength. At both ends of the radius, spongy bone columns contribute to the overall stability and resilience of the medullary cavity.
Proximal Extremity
The proximal extremity of the radius, also known as the elbow end, is comprised of several distinct structures. The head of the radius is cylindrical in shape and is located at the upper part of this region. It features a shallow cup that facilitates movement of the elbow joint. The majority of the head, as well as the neck, is smooth in texture, providing support to the overall structure.
Beneath these areas lies the radial tuberosity, which is divided into two regions for muscle insertion. One region is rough in texture, while the other is smooth. These regions allow for the attachment of muscles, enabling various movements and actions.