Midsagittal and axial cross-sectional wedge of a human head featuring structures involved in mastication (chewing), with emphasis on the tongue, teeth, and oral cavity. The adult jaw contains thirty-two permanent teeth which grind and tear food. Each tooth rises from a socket in the mandible or maxilla and consists of enamel-capped dentin surrounding a pulp cavity. Connective tissue, blood vessels, and nerve fibers that provide the tooth with nutrients and sensation enter the tooth through the apical foramen at the bottom of the root; here the cavity is called the root canal. The tongue and the teeth work together to form a bolus, a mass of chewed food. The tongue also aids in swallowing and is essential for human speech. In addition, the papillae that cover its surface provide friction for moving food around the mouth; two of the three kinds of papillae house taste buds.