Shoulder in : Passive range-of-motion screen · 499

The shoulder is the most mobile joint in the human body, formed where the ball of the upper arm bone sits in a shallow socket of the shoulder blade. This shallow fit allows an exceptional range of motion but provides little inherent bony stability, so the joint depends heavily on the surrounding rotator cuff muscles, ligaments, and labrum to stay centered during movement.

Shoulder pain is among the most common musculoskeletal complaints, particularly among adults over 40 and those in occupations or sports involving repeated overhead motion. Rotator cuff-related conditions account for a large share of cases, ranging from irritation of the tendons to partial or full tears.

The rotator cuff is a group of four muscles — supraspinatus, infraspinatus, teres minor, and subscapularis — whose tendons wrap around the shoulder joint and help keep the arm bone centered in its socket while allowing rotation. Does a rotator cuff tear always need surgery? Many partial and even some full-thickness tears, especially in less active or older individuals, are managed successfully with structured exercise; surgery is more often considered for larger tears, significant weakness, or failed conservative care.