A female developed 'pointing index' after an accident. This is due to injury to the following nerve?

In high median nerve lesions, the long flexors to the thumb and index fingers are also paralysed and the patient shows the 'pointing index' sign. High lesions are generally due to forearm fractures or elbow dislocation. Ref: Apley's System of Ohopaedics and Fractures By Louis Solomon, David Warwick, Selvadurai Nayagam, 2010, Page 284.