His jaw was clenching and unclenching.
His jaw was clenched and ticking as the muscles jumped.
The lower jaw is large, especially the region of the angle, which is expanded and flattened, giving great surface for the attachment of the masseter muscle.
With 14, 15 or 16 pairs of claw-bearing ambulatory legs, with three spinous pads on the legs, and nephridial opening of the 4th and 5th legs on the proximal pad; feet with one anterior, one posterior and one dorsal primary papilla; inner jaw without diastema, outer with or without a minor tooth.
The skin against his jaw was rough.
Gabriel rubbed his jaw and strode out of the Oracle's small room.
The condyle of the lower jaw is antero-posteriorly elongated.
There was something else in her gaze and the firm set of her jaw that bothered him.
Everything from his unshaven jaw to his crooked nose drew her hungry gaze, and she took him in, feeling as if she'd never truly seen him before.
The bluish pearl-white of the inside of the jaw was within six inches of Ahab's head, and reached higher than that.