Translation of "Bellying" in Portuguese

"So saying, his mighty spear, with all his force, / full at the flank against the ribs he drave, / and pierced the bellying framework of the horse. / Quivering, it stood; the hollow chambers gave / a groan, that echoed from the womb's dark cave."

"Tendo falado assim, com toda a força / arroja enorme lança contra o flanco / bojudo do artefato gigantesco. / Lá encravada, ela ficou vibrando / e as cavernas equinas, abaladas, / um surdo e cavo som repercutiram."