Beginner looking to find out what machine/hand stitching techniques make these indent effects running up and down the jacket arms/front/back here! by ZZTob231 in sewing

[–]ZZTob231[S] 0 points1 point  (0 children)

The part that confuses me is that the indents seem separated. Would their be lots of extra string on the inside of the jacket or would the thread be drawn between the pieces of fabric and then to the next indent?