Jaw: Definition

JAW definition: 1. the lower part of your face that moves when you open your mouth: 2. either of the two bones in…. Learn more. Learn about the anatomy and functions of the upper and lower jaws, the bones, joints and muscles involved in mastication. The web page also explains the difference between the maxilla and the mandible, and the temporomandibular joint. Jaw pain may be caused by various factors, such as grinding your teeth, gum disease, infections or injuries. Learn how to prevent and treat jaw pain, when to call a healthcare provider and what to do in an emergency. Your jaw plays a crucial role in your day-to-day life, from chewing food to speaking clearly. Yet, it's often overlooked until something goes wrong.