Proximal radioulnar joint

A pivotal joint in the forearm, facilitating the rotation of the radius around the ulna.

The proximal radioulnar joint is a synovial pivot joint located near the elbow where the head of the radius articulates with the radial notch of the ulna. This connection allows for the rotation of the forearm and the ability to turn the palm up (supination) and down (pronation).

Terminologia Anatomica

articulatio radioulnaris proximalis

System

Skeletal system

Function

The main function of the proximal radioulnar joint is to enable the rotation of the forearm. During activities such as twisting a doorknob or turning a screwdriver, the radius rotates around the fixed ulna. This movement is essential for various daily activities, allowing for complex hand positions and facilitating the grip and manipulation of objects. Furthermore, the joint plays a significant role in overall arm mobility and stability, making it integral to the biomechanics of the upper limb. The joint is stabilized by the annular ligament, which encircles the head of the radius and maintains its position against the ulna, allowing for smooth and controlled movements during rotational activities.

Location

The proximal radioulnar joint is situated near the elbow, specifically at the superior end of the forearm. This joint is formed as the rounded head of the radius fits into the radial notch of the ulna. The radial notch is located on the lateral aspect of the ulna and is positioned just below the elbow joint. The proximity of this joint to the elbow allows it to work in conjunction with the humeroulnar joint (part of the elbow) to facilitate complex movements of the arm. The joint is easily palpable near the outer side of the elbow, and its position is crucial for the forearm's dynamic motion.

Did You Know?

The proximal radioulnar joint allows for a range of motion estimated at up to 180 degrees during pronation and supination.
Injuries to this joint, such as nursemaid's elbow, commonly occur in children when the arm is pulled forcefully.
The annular ligament not only stabilizes the joint but also acts as a fulcrum, allowing the radius to rotate smoothly around the ulna.