the xiphoid process, a small cartilaginous extension to the lower part of the sternum, usually ossified in the adult human.
i just discovered i have gallstones after two trips to the er/ed in the last two and a half months. my pain began as a severe clenching pain under my xiphisternum (directly under my ribs in the centre). it was cyclic and lasted 45 minutes or so each time and having just had a baby, i likened it to contractions, but under my ribs rather than in my abdomen. i have also had episodes of back pain centered at the level of my shoulder blades, which i now wonder were related to the gall stones as they were often after eating. i had an ultrasound this morning which revealed a lovely collection (30 or so) small gallstones. at least i now know what it is. medicinenet.com