What is the term for the lower part of your face that moves when you open your mouth?

The term for the lower part of your face that moves when you open your mouth is "jaw." The jaw consists of the mandible, which is the bone that forms the lower part of the skull and holds the lower teeth in place. It allows for the movement necessary for activities such as chewing and speaking, making it a crucial component of facial function and expression.

The other choices refer to different facial features. The "chin" is the prominent part of the jawbone located at the lower front of the face, while the "mouth" refers to the opening where food enters and is involved in speech, but does not specifically denote the moving structure. The "cheek" pertains to the fleshy part of the face below the eyes and to the side of the mouth, which does not play a direct role in the movement associated with opening the mouth.