In shoulder impingement, which muscle is most commonly affected?

In shoulder impingement, which muscle is most commonly affected?

• A. Supraspinatus
• B. Infraspinatus
• C. Subscapularis
• D. Deltoid

Answer: (A)

Shoulder impingement happens when soft tissues in the subacromial space are pinched as the arm lifts. The supraspinatus tendon is most commonly affected because it travels directly under the acromion and works at the very start of arm elevation, bearing a high load during this motion. Its path under the acromial arch makes it particularly vulnerable to compression and repetitive microtrauma, leading to tendinopathy or partial tears. Other rotator cuff muscles can be involved in impingement, but far less often, and the deltoid isn’t typically a primary site of impingement pathology. So the supraspinatus is the usual culprit in this condition.

Shoulder impingement happens when soft tissues in the subacromial space are pinched as the arm lifts. The supraspinatus tendon is most commonly affected because it travels directly under the acromion and works at the very start of arm elevation, bearing a high load during this motion. Its path under the acromial arch makes it particularly vulnerable to compression and repetitive microtrauma, leading to tendinopathy or partial tears. Other rotator cuff muscles can be involved in impingement, but far less often, and the deltoid isn’t typically a primary site of impingement pathology. So the supraspinatus is the usual culprit in this condition.