Which muscle is tight in Upper Cross Syndrome?

• A. Pectoralis minor
• B. Latissimus dorsi
• C. Tibialis anterior
• D. Biceps brachii

Answer: (A)

Upper Cross Syndrome features a pattern of tightness and weakness that creates a forward, rounded shoulder posture. The pectoralis minor is the muscle most commonly tight in this pattern because it attaches from the ribs to the coracoid process of the scapula. When it tightens, it pulls the scapula into protraction and downward tilt, contributing to the rounded shoulders and restricted upward rotation during arm elevation. This anterior pull on the scapula also tends to inhibit the stabilizing muscles that position the shoulder blade, worsening the imbalance.

The other muscles listed don’t fit this classic pattern. Latissimus dorsi can influence shoulder movement but isn’t the hallmark tight muscle in Upper Cross Syndrome. Tibialis anterior is a leg muscle and unrelated to the shoulder posture described. Biceps brachii isn’t typically the tight muscle driving the characteristic posture either.