skip to main content

Cricothyroid Membrane Surface Anatomy — FRCA Primary MCQ

Instant feedback + full explanation. One question, done properly.

HardAnatomyCricothyroid Membrane Surface AnatomyFRCA Primary

During ultrasound-guided infraclavicular needling, the needle becomes almost perpendicular to the beam and its image disappears. Which adjustment most directly restores needle visibility?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: B — Heel-toe the probe towards a perpendicular beam–needle angle

The best answer is “Heel-toe the probe towards a perpendicular beam–needle angle”. Needles are specular reflectors and return the strongest echo when the ultrasound beam is close to perpendicular to their surface. Heel-toe adjustment can improve this angle and restore visibility. Doppler wall filter, pulse-repetition frequency, colour gain and continuous-wave mode address flow imaging rather than needle anisotropy.

Reference: Gupta et al., Potential role of ultrasound in anesthesia and intensive care: https://pmc.ncbi.nlm.nih.gov/articles/PMC4173359/