College of Massage Therapists of British Columbia (CMTBC) Practice Exam

Which muscle might be involved if Adson's Maneuver is positive and the patient has symptoms consistent with anterior scalene compression?

1. Subscapularis

2. Latissimus Dorsi

3. Scalenes

4. Serratus Anterior

The correct answer is: Scalenes

A positive Adson's Maneuver indicates the possibility of thoracic outlet syndrome, particularly involving the subclavian artery and lower trunk of the brachial plexus. When symptoms are present that are consistent with anterior scalene compression, the scalene muscles, especially the anterior scalene, are directly implicated. The scalenes are a group of muscles located in the lateral neck, including the anterior, middle, and posterior scalene. The anterior scalene muscle is situated in close proximity to the brachial plexus and the subclavian artery, which can be compressed during specific positional changes, leading to vascular and neurological symptoms. Recognizing the function and anatomy of the scalenes is crucial in understanding how they can contribute to thoracic outlet syndrome. Therefore, the involvement of the scalenes in a positive Adson's maneuver aligns with the symptoms stemming from compression occurring in this area, clarifying why this option is the correct choice. The other muscles listed do not have the same anatomical relationship to the thoracic outlet or the symptoms noted in this context, making them less relevant to the scenario described.