There is a direct route from Nisalgaon to Shimengaon, following the river (Panjyan Khola), marked on most maps. In practice, the trail is impassable as it would require wading in deep, icy cold water. This is the reason why the usual trekking trail does the bypass through Musigaon and Musi La (5050 m).
The picture is taken at the place where the trail veers left (North-East), towards Musigaon.