He paused a moment, and a muscle beside his mouth jerked and was still.

A muscle jerked in his jaw, and he grabbed his hat.

The arms, legs, torso, or facial muscles jerk rapidly as though they are being shocked.

The small muscles in my arms jerked with it.

Each time she raised the ax, her muscles quivered and jerked.

A muscle jerked at the corner of his mouth.

The small muscles along his jaw jerked and quivered as she moved her fingers over the wound.

Every muscle in Brennan jerked as he saw it.

A muscle in his cheek jerked, but his eyes stayed level.

His muscles might be jerking, but his voice was rock steady.