Nerve II

A 30 year old woman undergoes a prolonged pelvic surgery in lithotomy position. Post-operatively, she is noted to have acute foot drop. She cannot dorsiflex her foot against resistance; in order to walk, she has to flex her hip higher when walking. She also complains of loss of sensation over the top of her foot. Although she cannot evert her foot, inversion is preserved.

Challenge: Where's the lesion?

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