Neuroanatomy · NEET PG Preparation Anatomy
During a neurological examination, a patient is asked to look to the far left. The left eye abducts normally, but the right eye fails to adduct, acco…
Practice question from Neuroanatomy (NEET PG Preparation Anatomy), with the correct answer and a step-by-step solution.
hard · MCQ · Q-4B6618
During a neurological examination, a patient is asked to look to the far left. The left eye abducts normally, but the right eye fails to adduct, accompanied by horizontal nystagmus of the abducting left eye. Where is the most precise site of the lesion?
- A.Right abducens nucleus
- B.Left medial longitudinal fasciculus
- C.Right medial longitudinal fasciculusCorrect answer
- D.Left oculomotor nerve
Solution
This clinical presentation is classic for internuclear ophthalmoplegia (INO). The lesion lies in the medial longitudinal fasciculus (MLF) ipsilateral to the adduction failure. For left gaze, the right MLF is responsible for communicating signals from the left abducens interneurons to the right oculomotor subnucleus for medial rectus contraction.
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