Development
During the development of an embryo, the bones start off soft and pliable. However, as the process of ossification takes place, the ulna undergoes significant changes. Ossification involves the hardening and reshaping of the bone, resulting in the ulna being considerably thicker than the radius when a child is between four and five months old. Once the bone has fully developed, the ulna is only half as thick as the radius.
What is the Interosseous Membrane?
The interosseous membrane of the forearm is a distinctive tissue that connects the interosseous borders of the ulna and radius. Apart from the numerous forearm muscles, the ulna also provides attachment points for this long, fibrous sheet. While it does have attachment sites for muscles, its primary role is to redistribute compressive loads from the radius onto the ulna. This crucial function ensures the protection of individual joints against potential damage caused by excessive loads. For instance, a handstand is an action that can trigger this shift in load distribution.