body part vs external body part

Other hyponyms of body part include saddle, underpart, horseback, dock, ambulacrum, withers, cannon, shank, loin, lumbus, croup, croupe, hindquarters, rump, gaskin, flank, thorax, apparatus, adnexa, annexa, area, region, dilator, groove, vallecula, partition, anatomical structure, bodily structure, body structure, complex body part, structure, fornix, system, ampulla, tissue, mentum, organ, venter, energid, protoplast, appendage, outgrowth, process, lobe, rectum, shoulder, body, torso, trunk, chest, pectus, thorax, thorax, hip, haunch, abdomen, belly, stomach, venter, dorsum, back, dorsum, small, arse, ass, backside, behind, bottom, bum, buns, butt, buttocks, can, derriere, fanny, fundament, hind end, hindquarters, keister, nates, posterior, prat, rear, rear end, rump, seat, stern, tail, tail end, tooshie, tush, buttock, cheek, stump, shank, shin, toe, articulatio, articulation, joint, loins, feature, lineament, rudiment.