Brachial Plexus Roots — FRCA Primary MCQ

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EasyAnatomyBrachial Plexus RootsFRCA Primary

In its usual anatomical configuration, the brachial plexus is formed from the anterior rami of which spinal nerves?

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Correct answer: B — C5–T1

Explanation lettering: E = shown as B · D = shown as C · B = shown as D · C = shown as E

The correct answer is E. The usual brachial plexus is formed by the anterior rami of C5, C6, C7, C8 and T1. C5 and C6 unite as the upper trunk, C7 continues as the middle trunk, and C8 and T1 unite as the lower trunk. Options B and C are plausible because anatomical variants occur: a prefixed plexus may receive a C4 contribution, whereas a postfixed plexus may receive a T2 contribution. These are variants rather than the usual configuration. Option A omits C5, and option D omits the lower cervical and first thoracic contributions.

Reference: Rupnik B. Anatomical basic knowledge for the occasional RA anesthesiologist: The Origin of the Brachial Plexus—The Roots and Trunci. Regional Anesthesia & Pain Medicine. 2024;49(Suppl 1):A373.2. https://rapm.bmj.com/content/49/Suppl_1/A373.2