Corticospinal Decussation Pyramids — FRCA Primary MCQ
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Correct answer: D — The pyramidal decussation at the cervicomedullary junction
The best answer is “The pyramidal decussation at the cervicomedullary junction”. Approximately 80–90% of corticospinal fibres decussate in the caudal medulla at the pyramidal decussation and descend as the lateral corticospinal tract. A smaller anterior corticospinal component remains uncrossed initially and may cross near its spinal target. The internal capsule and brainstem pathways precede, rather than perform, the principal decussation.
Reference: Royal College of Anaesthetists, Primary FRCA Syllabus 2021: https://www.rcoa.ac.uk/sites/default/files/documents/2026-01/Primary-FRCA-Syllabus.pdf