Jaws (also known as the mandible) are a pair of bones that form the framework of the mouth. They are attached to the rest of the skull at the temporomandibular joints (TMJ). The lower jaw, or mandible, is a U-shaped bone that articulates with the temporal bone at the TMJ. It provides support for the teeth and gives shape to the face. The upper jaw, or maxilla, is fused to the rest of the skull and does not move. It supports the teeth and forms part of the orbit (eye socket).
The jaws are used for chewing, biting, and swallowing. Chewing is a complex process that involves both voluntary and involuntary muscles. The masseter muscle is responsible for closing the jaw; it is one of four muscles that make up what is known as “the chewing quadrilateral”. The other three muscles are involved in openingthejaw:thetemporalis , medius ,and anterior belliesofdigastric .Bitingis a reflexive action mediated by nerves inthejawthat respondto pressure on themolars .Swallowingis a coordinated effort between various musclesinvolving boththe mouth and throat .
Teeth are embedded in sockets in both jaws and are held in place by ligaments. There are two sets of teeth: primary (or “baby”) teeth and permanent teeth. Primary teeth typically erupt between 6 months and 3 years of age; they are eventually replaced by permanent teeth. Adults have 32 permanent teeth: 16 in each jaw. These include 4 incisors (front), 4 canines (cuspids), 8 premolars (bicuspids),and 12molars(including4 wisdomteeth ). Teeth serve several functions: they help with chewing, enable us to speak clearly, contribute to facial appearance,and play an important role inthe healthof overall oral cavity .