A physical therapist observes a patient from behind during bilateral shoulder abduction and notes that the patient's right scapula is more abducted than the left scapula at the end range of movement. Which of the following conditions is the MOST likely cause of the altered scapula position on the right?

A physical therapist observes a patient from behind during bilateral shoulder abduction and notes that the patient's right scapula is more abducted than the left scapula at the end range of movement. Which of the following conditions is the MOST likely cause of the altered scapula position on the right?

• A. Tightness of the Rhomboid Major and Minor
• B. Weakness of the Serratus Anterior
• C. Restricted Motion of the Glenohumeral Joint
• D. Weakness of the Upper Trapezius

Answer: (C)

During shoulder abduction, most movement comes from the glenohumeral joint, while the scapulothoracic articulation provides upward rotation and position to allow full elevation. If the glenohumeral joint motion is restricted on one side, the arm can’t reach the end range through the humerus alone, so the scapula compensates by moving more into protraction (appearing more abducted) to help achieve the available range. This pattern points to a mechanical limitation at the glenohumeral joint rather than a weakness or tightness of scapular stabilizers. Tight rhomboids would pull the scapula toward the spine (more retraction, not protraction). Serratus anterior weakness tends to cause medial border winging and insufficient upward rotation rather than isolated increased scapular abduction at end range. Weakness of the upper trapezius would alter elevation and upward rotation but not explain unilateral excess scapular abduction at end range due to a joint restriction.

During shoulder abduction, most movement comes from the glenohumeral joint, while the scapulothoracic articulation provides upward rotation and position to allow full elevation. If the glenohumeral joint motion is restricted on one side, the arm can’t reach the end range through the humerus alone, so the scapula compensates by moving more into protraction (appearing more abducted) to help achieve the available range. This pattern points to a mechanical limitation at the glenohumeral joint rather than a weakness or tightness of scapular stabilizers.

Tight rhomboids would pull the scapula toward the spine (more retraction, not protraction). Serratus anterior weakness tends to cause medial border winging and insufficient upward rotation rather than isolated increased scapular abduction at end range. Weakness of the upper trapezius would alter elevation and upward rotation but not explain unilateral excess scapular abduction at end range due to a joint restriction.