What is the primary muscle suspected to be involved with Adson's Maneuver when testing for brachial plexus compression?

The primary muscle involved with Adson's Maneuver, which is used to test for brachial plexus compression, is the anterior scalene muscle. This maneuver assesses for potential compression of the neurovascular structures in the thoracic outlet, where the brachial plexus and subclavian artery can be affected by tightness or spasms in the anterior scalene.

During the test, the patient is instructed to turn their head toward the affected side, which can put additional stress on the structures passing through this area. If there is a reduction in pulse or reproduction of symptoms in the upper extremity, it suggests that the anterior scalene may be compressing the brachial plexus or associated vessels.

In contrast, the other muscles listed do not play a central role in this particular test or in the mechanics of thoracic outlet syndrome related to brachial plexus issues.