Musannaf Ibn Abi Shayba 18:103

Abu Bakr narrated to us, he said: Hatim ibn Wardan narrated to us, from Isma'il, from Makhul, who said: The *mudihah* (a wound that exposes the bone) is in the face and the head. However, if it is in the face and causes a disfigurement, then it is increased beyond the amount of the disfigurement.