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Supraclavicular Block Anatomy — FRCA Final MCQ

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ModerateRegional AnaesthesiaSupraclavicular Block AnatomyFRCA Final

A 60-year-old man (ASA II) requires an ultrasound-guided supraclavicular brachial plexus block for forearm surgery. In the transverse supraclavicular view, the trunks and divisions appear as a cluster of hypoechoic round neural elements posterolateral to the subclavian artery. Which pair should be identified as the key deep sonoanatomical landmarks before advancing the needle?

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Correct answer: B — First rib and pleura

The correct answer is B. At the supraclavicular level, the trunks and divisions of the brachial plexus form a hypoechoic cluster posterolateral to the subclavian artery and superficial to the first rib. The rib is hyperechoic, casts an acoustic shadow and can act as a bony backstop. The adjacent pleural line must also be identified and kept continuously clear of the needle because pleural puncture may cause pneumothorax. The subclavian vein is usually anteromedial rather than directly deep to the plexus. The vertebral artery and C7 transverse process are more relevant to lower interscalene imaging. The phrenic nerve lies on the anterior scalene muscle, while the thoracic duct is a left-sided lower-neck structure and is not a routine deep landmark for this block.

Reference: Lee MG et al. Ultrasound-guided central cluster approach for the supraclavicular brachial plexus block: a case series. Korean Journal of Anesthesiology. 2015;68(6):603-607. https://pubmed.ncbi.nlm.nih.gov/26634085/