Ohalos 1:8

There are 248 limbs (i.e., bones with flesh and sinew) that convey impurity in the human body: 30 in the foot, i.e., six per toe; ten in the ankle; two in the shin; five in the knee; one in the thigh; three in the hip; 11 ribs; 30 in the hand – six per finger; two in the forearm; two in the elbow; one in the upper arm; four in the shoulder. That makes 101 on each side (total: 202). There are 18 vertebrae in the spine; nine in the head; eight in the neck; six in the opening of the heart (i.e., the breast bones); five in the pelvis. Each of these limbs can convey impurity through contact, carrying or a tent, but only when they have a sufficient amount of flesh on them. If they don’t have the requisite volume of flesh on them, they can transmit impurity through contact and carrying but not through a tent.

Ohalos 2:1

The following things convey impurity through a tent: a corpse; an olive-sized piece of a corpse; an olive-sized portion of dissolved flesh from a corpse; a ladleful of corpse rot; the spine; the skull, a limb from a corpse or from a living person that has the requisite volume of flesh on it; a quarter-kav of bones (about a pint) from the greater part of the skeleton or the greater number of bones; the greater part of the skeleton or the greater number of bones from a corpse even if they don’t add up to a quarter-kav. All of these are ritually unclean. The greater number of bones is 125.