NBCE Exam 2026 – 400 Free Practice Questions to Pass the National Board of Chiropractic Examiners

In the context of Thoracic Outlet Syndrome (TOS), the scalene muscles, particularly the anterior and middle scalenes, are often implicated due to their anatomical location and function. These muscles are situated between the cervical spine and the first rib, which is a critical area where the brachial plexus and subclavian vessels pass.

When TOS occurs, it is frequently due to compression or entrapment of these neurovascular structures as they traverse the thoracic outlet. The scalenes are involved in causing such compression because they can become tight or hypertrophied, leading to a reduction in the available space for the surrounding neurovascular structures. This can result in symptoms such as neuropathy, pain, and vascular claudication in the affected arm.

While other muscles like the serratus anterior, pectoralis major, and latissimus dorsi play important roles in shoulder movement and stability, they are not typically the primary muscles associated with the compression phenomena seen in TOS. Understanding the role of the scalenes helps clarify why they are a central focus in discussions of Thoracic Outlet Syndrome.