Adam Clarke on 2 Samuel 20:10

In the fifth rib - I believe חמש chomesh, which we render here and elsewhere the fifth rib, means any part of the abdominal region. The Septuagint translate it την ψοαν, the groin; the Targum, the right side of the thigh, i.e., (the phrase of the Targumist being interpreted), the privy parts. That it means some part of the abdominal region, is evident from what follows, And shed out his bowels to the ground. It appears from this that, in plain English, he ripped up his belly.