How many degrees of freedom does the glenohumeral joint have?

The glenohumeral joint, commonly known as the shoulder joint, is classified as a ball-and-socket joint which allows for a wide range of motion. It has three degrees of freedom, meaning it can move in three different planes of motion:

1. Flexion and Extension – This movement occurs in the sagittal plane and involves raising the arm forward (flexion) and lowering it back down (extension).

2. Abduction and Adduction – This movement occurs in the frontal plane, where the arm can move away from the body (abduction) and back towards the body (adduction).

3. Internal and External Rotation – This movement occurs in the transverse plane, allowing the arm to rotate inward toward the body (internal rotation) and outward away from the body (external rotation).

The combination of these movements enables the shoulder to achieve significant mobility, making it capable of performing complex tasks. The presence of these three degrees of freedom distinguishes the glenohumeral joint as one of the most mobile joints in the human body.