Examples from the Web for midline
Nuchal: Width of anterior margin, 12 (estimated); greatest width, 37 (estimated); length at midline, 35 (estimated).
The red tips tend further to disrupt the body outline at the midline, or slightly posterior to this.Phylogeny of the Waxwings and Allied Birds|M. Dale Arvey
Third vertebral scute: Length of anterior margin, 33; greatest width, 42; length at midline, 40 (estimated).
The aorta and vena cava, the heart area, and then a midline incision was made.Warren Commission (3 of 26): Hearings Vol. III (of 15)|The President's Commission on the Assassination of President Kennedy
And they are both located approximately the same distance to the right of the midline of both garments.Warren Commission (5 of 26): Hearings Vol. V (of 15)|The President's Commission on the Assassination of President Kennedy