下顎[kagaku] lower jaw
二重顎[nijuuago] double chin
顎骨[agobone] jawbone
上顎[uwaago] upper jaw
顎紐[agohimo] chin strap

顎ひげ[agohige] beard (esp. on the chin)
下顎骨[kagakukotsu] mandible
顎関節[gakukansetsu] jaw joint
顎で使う[agodetsukau] to set somebody to work in an arrogant fashion

せん状骨[senjoukotsu] scaphoid bone (in wrist near thumb)
遺骨[ikotsu] remains
化骨[kakotsu] ossification
会厭軟骨[eennankotsu] epiglottis
がい骨[gaikotsu] skeleton

雁骨[kariganebone] scapula
気骨[kikotsu] (moral) backbone
侠骨[kyoukotsu] chivalrous spirit
胸骨[kyoukotsu] breastbone
筋骨[kinkotsu] muscles (sinews) and bones