Head anatomy. Anatomical model of a dissected head and throat. The model shows internal organs such as the brain (grey, upper left). The lower jaw has been partially removed (centre right) to show details of mouth anatomy. The right maxillary sinus (red, upper centre) is a hollow in the bone of the right-hand side of the face below the eye. Together with the other sinuses, it reduces the skull's weight. The larynx (white, lower centre) is a throat structure that lies above the trachea (airway to the lungs) and produces the resonance of speech. Below the larynx is the thyroid gland (purple, double-lobed) that is involved in the regulation of the metabolic rate.