胸腔[kyoukou] thorax
口腔外科[koukuugeka] dental surgery
耳腔[jikou] inside the ear
体腔[taikou] body cavity
体腔壁[taikouheki] body wall

内腔[naikou] lumen (anatomical)
口腔[koukou] the oral cavity
鼻腔[bikou] the nasal cavity
腹腔[fukkou] abdominal cavity
口腔癌[koukougan] oral cancer