Another term for inside leg.Measure the pants crotch length from the inseam to the waistline and record on the pattern....
To measure the length of your inseam, lay a pair of trousers that fit you well flat on the table as aforementioned, and measure them from the top of the inner pant leg seam to the opening at the bottom of the leg.
Also, any hints on where I can find lengthier inseams might help, if you're feeling especially generous.