On the navel circle, knowledge of the plan of the body
By making saṃyama on the navel circle, he apprehends the plan of the body. There are three humours (doṣa, which harm by excess): wind, bile, and phlegm. The corporeal elements (dhātu) are seven: skin, blood, flesh, fat, bone, marrow, and semen; the order of the list is, that each is exterior to the one which it precedes.
… wind, bile, and phlegm, and their proportions and their seats, etc. become knowable to him.
Then The corporeal elements (dhātu) are seven, in fixed relations of exterior and interior to each other. Skin is outside them all; next within is blood, and then flesh, and then fat, then bone, then marrow, and then semen, which is the most interior of all. The order of the list is, that each is exterior to the one which it precedes. Similarly he will come to know the plan of the nerves.