jaw
「顎」 has another reading with different meanings.
jaw; chin
顎関節症のせいで口を開けるのが辛い。
Opening my mouth is painful due to TMJ disorder.
恐竜の顎の化石が今日発見された。
A fossil of a dinosaur jaw was discovered.
人類の顎は進化とともに小さくなった。
Human jaws have become smaller through evolution.