A 58-year-old hypertensive man develops sudden-onset left hemiplegia with deviation of the head and eyes to the RIGHT and preserved consciousness. Damage to which structure best explains the conjugate eye deviation toward the right?

• A Right frontal eye field (Brodmann area 8) ✓
• B Left frontal eye field (Brodmann area 8)
• C Right paramedian pontine reticular formation (PPRF)
• D Left medial longitudinal fasciculus

Explanation

Voluntary conjugate gaze is driven by the frontal eye fields, which project contralaterally to the PPRF. Destruction of the right frontal eye field removes its drive to the left PPRF, so the left PPRF's unopposed contralateral competitor (the right PPRF) drives the eyes to the right — i.e., eyes deviate toward the side of the lesion. Left hemiplegia confirms right hemispheric involvement, and preserved consciousness indicates the lesion is supratentorial rather than in the brainstem reticular formation.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.