Sectional density is a very important aspect of a projectile or bullet, and is for a round projectile like a bullet the ratio of frontal surface area ( half the bullet diameter squared, times pi ) to bullet mass.
12.
The frontal margin of the pancreas separates the inferior surface of the pancreas, and along this border the two layers of the transverse mesocolon diverge from one another; one passing upward over the frontal surface, the other backward over the inferior surface.