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

What is the correct order of structures in the brachial plexus?

1. Roots, branches, cords, divisions, trunks

2. Trunks, divisions, branches, cords, roots

3. Roots, trunks, divisions, cords, branches

4. Cords, roots, branches, trunks, divisions

The correct answer is: Roots, trunks, divisions, cords, branches

The correct sequence of structures in the brachial plexus is roots, trunks, divisions, cords, and branches. This anatomical arrangement reflects the organization of the plexus and is crucial for understanding the innervation of the upper limb. Starting with the roots, these are the anterior rami of spinal nerves C5 to T1. These roots converge to form three trunks. Each trunk then splits into two divisions, leading to an arrangement that can be visualized as a tree with branches. Following the divisions, the structure transitions into three cords, which are named based on their relationship to the axillary artery. Finally, branches emerge from these cords, leading to the major peripheral nerves that innervate the arm and hand. This structured progression from roots to branches allows for clarity in clinical assessments and interventions involving nerve injuries or pathologies in the upper extremity. The understanding of this order is essential for anatomy students as well as practitioners involved in diagnosing and treating conditions affecting upper limb functionality.