What is the combined arthrokinematic action of the humeral head on the glenoid during flexion?

During shoulder flexion, the humeral head exhibits a specific arthrokinematic pattern to maintain proper joint mechanics and stability in the glenohumeral joint. When the arm is being raised forward (flexion), the humeral head rolls posteriorly while simultaneously gliding anteriorly. This combination allows for an optimal fit between the humeral head and the shallow glenoid cavity, preventing impingement and ensuring that the joint functions smoothly.

The posterior roll of the humeral head during flexion allows the arm to move upwards effectively, while the anterior glide helps to maintain contact and alignment in the joint, preventing excessive compression or instability. This combined action is critical not only for achieving the desired range of motion but also for protecting the structures surrounding the shoulder joint from injury during movement. Understanding this kinematic pattern is essential for assessing shoulder function and developing appropriate rehabilitation strategies for injuries or dysfunction.