Ulna

The ulna is one of two bones in the forearm, it lies medial to the radius and is categorized as a long bone. The ulna and radius work together, with the ulna providing a stabilizing role while the radius serves as the pivot to produce movement.

The parts of the ulna can be categorized as:

Radius

The radius is one of two bones in the forearm, it lies lateral to the ulna and is categorized as a long bone. The radius pivots around the radial notch of the ulna to produce supination and pronation movements at both proximal and distal radio-ulnar joints. The radius articulates with the carpal bones.

The parts of the radius can be categorized as:

Clinical Notes:

1. The transmission of force can be simplified with the following steps:

   • metacarpals -> carpals -> radius -> interosseous membrane -> ulna -> humerus -> scapula -> clavicle -> thorax

2. Due to the tight proximity of the radius and ulna, a fracture in one typically results in the dislocation of the other.