Physical Therapy Assistant Practice Exam

Which muscle is primarily responsible for adducting and downwardly rotating the scapula?

1. Rhomboids

2. Latissimus dorsi

3. Middle trapezius

4. Serratus anterior

The correct answer is: Rhomboids

The rhomboids are primarily responsible for adducting the scapula, which involves drawing the scapulae towards the spine. They also assist in the downward rotation of the scapula, which occurs when the inferior angle of the scapula moves medially and the glenoid cavity tilts inferiorly. This action is essential for various movement patterns and postural stability. When considering the other muscles listed, while they all play important roles in scapular movement, they do not primarily fulfill both functions – adduction and downward rotation – as effectively as the rhomboids. The latissimus dorsi is primarily known for its role in shoulder extension, adduction, and internal rotation, but it does not directly contribute to the scapular movements specified. The middle trapezius does assist with scapular adduction but does not have a strong influence on downward rotation. The serratus anterior primarily functions in scapular protraction and upward rotation, playing a contrasting role to what the question identifies. Therefore, the rhomboids stand out as the correct choice for the actions described.