Glosaurus
Human Anatomy

Annular ligament

A fibrous band that stabilizes the radius bone in the forearm at the elbow joint.
The annular ligament encircles the head of the radius, adhering it to the ulna at the proximal radioulnar joint. This ligament is crucial for the stability and function of the elbow joint, allowing for the rotation of the radius during forearm motion.
Terminologia Anatomica
ligamentum annulare
System
Skeletal system
Function
The primary function of the annular ligament is to stabilize the radial head, ensuring that it remains properly seated within the joint while allowing for the necessary movement of the forearm. This stabilization is essential during rotational motions, such as turning the palm up or down. The ligament acts as a protective band around the radial head, preventing dislocation and facilitating smooth movements between the radius and ulna. Without the annular ligament, the radius could potentially shift out of place during forearm rotation, leading to pain and decreased mobility. Overall, the annular ligament plays a pivotal role in maintaining the integrity of the elbow and forearm function, enabling activities that require fine motor skills as well as heavier lifting.
Location
The annular ligament is located around the proximal end of the radius, specifically at the elbow joint where the radius and ulna articulate. It forms a ring-like structure that directly connects to the ulna, encircling the radial head. This positioning allows it to function in conjunction with surrounding muscles and tendons, providing both support and mobility. The ligament can be palpated on the lateral side of the elbow and is closely associated with other structures in the area, including the elbow flexors and extensors, which further emphasize its integral role in forearm mechanics.
Did You Know?
  • The annular ligament is sometimes referred to as the 'ligament of the radius' because of its specific attachment around the radial head.
  • In children, injuries to the annular ligament are commonly associated with a condition called 'nursemaid's elbow,' which occurs when the ligament slips over the radial head.
  • Unlike many other ligaments in the body, the annular ligament is not a fixed structure but rather has some degree of elasticity, allowing it to accommodate the movements of the forearm.