Ulnar collateral ligament

Essential for stabilizing the inner aspect of the elbow joint during movement.

A critical ligament located in the elbow, the ulnar collateral ligament (UCL) connects the upper arm bone (humerus) to the forearm bone (ulna). It plays a key role in reinforcing the joint's strength and stability, particularly during activities that involve throwing or overhead motions. The UCL is composed of three distinct bundles that work together to resist stresses placed on the elbow.

Terminologia Anatomica

ligamentum collaterale ulnare

System

Musculoskeletal system

Function

The primary function of the ulnar collateral ligament is to provide stability to the elbow joint, particularly during activities that place significant stress on this area, such as throwing sports or certain weight-bearing exercises. It helps to prevent the elbow from bending inwards (valgus stress) which can lead to instability and injury. When the arm is raised above the head or when throwing, the UCL is subjected to high tension, making its integrity essential for maintaining proper joint function. Injuries to the UCL can result in pain, swelling, and functional limitations, often necessitating rehabilitation or even surgical intervention, such as Tommy John surgery, to restore full function and strength to the elbow.

Location

The ulnar collateral ligament is located on the medial (inner) side of the elbow joint. It extends from the medial epicondyle of the humerus, which is the bony prominence on the inner part of the upper arm, to the proximal ulna, which is the bone in the forearm that runs parallel to the radius. Its positioning allows it to effectively stabilize the elbow during flexion and extension, particularly when the arm is subjected to forces that could compromise its structural integrity. The ligament is situated within the joint capsule, beneath the skin, making it essential but somewhat vulnerable to injury in athletes and individuals engaged in repetitive overhead arm movements.

Did You Know?

The ulnar collateral ligament is most commonly injured in baseball pitchers due to the high demands placed on the elbow during throwing.
Reconstruction of the UCL using a tendon graft, known as Tommy John surgery, has become a common procedure for athletes to regain elbow stability.
The three distinct bundles of the UCL each have different roles, contributing to the ligament's overall ability to withstand various types of stress.