According to Semon's law, in a slowly progressive organic lesion of the recurrent laryngeal nerve:

• A Adductor fibres are paralysed before abductor fibres
• B Only the cricothyroid muscle loses function
• C All fibres are affected simultaneously, giving the cadaveric position
• D Abductor fibres are paralysed before adductor fibres, leaving the cord near the paramedian position ✓

Explanation

Semon's law states that in progressive organic RLN palsies the abductor (posterior cricoarytenoid) fibres fail first, so the cord remains near the paramedian position and airway compromise is limited. The widely taught explanation is that abductor fibres occupy a more vulnerable position in the nerve trunk. The law is a clinical observation with exceptions, but Indian examination convention treats it as standard, and it explains why unilateral palsy causes hoarseness without stridor.

Reference: Dhingra's Diseases of Ear, Nose and Throat, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.