2,341. The Difference Between the Kidney Membranes

Maachalos Assuros 7:11

There are five cords in the flanks: three on the right side and two on the left. The three on the right each divide into two and two on the left each divide into three. All of these are prohibited as forbidden fats, as are the cords that run from the spleen and the kidneys. The membranes on the spleen, over the flanks and on the kidneys are likewise prohibited as forbidden fats. One is liable to kareis for eating the membrane on the thick side of the spleen; the rest of this membrane is likewise prohibited but one is not culpable for eating it.

Maachalos Assuros 7:12

There are two membranes on the kidney; one would be liable for kareis for the upper one like the actual fat of the kidney, but the lower one is like other membranes. The cords in them are prohibited but one is not liable to kareis for eating them.